Math
1,470 math calculators: percentages, fractions, equations, geometry, trigonometry, statistics and number theory. Each one shows the method in plain words, so you get the answer and understand how it was reached, free in your browser.
Perpendicular bisector calculator
For the segment from (0, 0) to (4, 6), the perpendicular bisector passes through the midpoint (2, 3) and is the line 2x + 3y − 13 = 0.
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Point in triangle checker
The point (1, 1) lies inside the triangle with corners (0, 0), (4, 0) and (0, 3), whose area is 6.
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Point to plane distance calculator
The point (1, 1, 1) sits four thirds of a unit, 1.333333333333, from the plane 2x + y + 2z − 9 = 0.
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Point-slope form calculator
Enter a point and a slope and get the line's equation two ways: the point (1, 2) with slope 3 gives y − 2 = 3(x − 1), and the same line crosses the y-axis at…
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Number of sides from interior angle calculator
Enter one interior angle of a regular polygon and get its number of sides: 108° gives 5 sides, a pentagon, with an exterior angle of 72°.
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Sum of interior angles calculator
Enter the number of sides and get the total of all interior angles of any simple polygon: a pentagon adds up to 540°, regular or not, because it splits into…
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Prism volume calculator
Enter the area of the base and the height of a right prism and get its volume: a base of 12 and a height of 5 hold 60 cubic units, whatever the shape of the…
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Prolate spheroid calculator
Enter the equatorial and polar radii of a stretched sphere, such as a rugby ball or an elongated tank end, and get its exact volume, four thirds of π times a²…
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Pyramid lateral surface area
Enter the base perimeter and the slant height of a regular pyramid and get the area of its triangular faces: a perimeter of 40 and a slant height of 12 give…
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Quadrilateral area from diagonals calculator
Enter the two diagonals of a quadrilateral and the angle between them and get its area: diagonals of 6 and 8 crossing at 90° enclose 24, half their product…
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Quarter circle area calculator
Enter a radius and get the area of a quarter circle and the length of its curved edge: a radius of 2 gives an area of exactly π and an arc of the same length.
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Rectangle area calculator
Enter the length and width of a rectangle and get its area: a length of 8 and a width of 5 give 40, the figure you need for a floor, a patio slab or a garden…
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Rectangle sides from area and ratio
Give the area of a rectangle and how many times longer it is than wide, and get both sides: an area of 48 with a ratio of 3 gives a length of 12 and a width of…
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Rectangle perimeter calculator
Enter the length and width of a rectangle and get the distance around it: 10 and 5 give a perimeter of 30, twice their sum, ready for fencing, trim or…
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Reflect a point over the x-axis calculator
Enter a point and get its mirror image across the x-axis: (3, 5) becomes (3, −5), because only the vertical coordinate changes sign.
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Reflect a point over the y-axis calculator
Enter a point and get its mirror image across the y-axis: (3, 4) becomes (−3, 4), since the horizontal coordinate changes sign and the height stays the same.
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Reflect a point over y=x calculator
Enter a point and get its mirror image across the diagonal line y = x: (3, 7) becomes (7, 3), because the two coordinates simply trade places.
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Regular polygon central angle calculator
Enter the number of sides of a regular polygon and get the angle at its center between two neighbouring corners: a regular pentagon has a central angle of 72°…
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Regular polygon diagonal lengths
Enter the number of sides and the circumradius of a regular polygon and get each distinct diagonal length: a hexagon with a radius of 1 has 6 short diagonals of…
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Rhombic triacontahedron calculator
Enter the edge length of a rhombic triacontahedron, the 30-face Catalan solid behind many zomes and decorative shells, and get its volume and surface area: an…
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Rhombicosidodecahedron calculator
Enter the edge length of a rhombicosidodecahedron and get its exact volume and total surface area: an edge of 1 gives a volume of about 41.6153237825 and a…
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Rhombicuboctahedron calculator
Enter the edge length of a rhombicuboctahedron, the solid of 8 triangles and 18 squares, and get its volume and surface area: an edge of 1 gives about…
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Rhombus area from diagonals calculator
Enter the two diagonals of a rhombus and get its area as half their product: diagonals of 6 and 8 give an area of 24, with no side length or angle needed.
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Rhombus perimeter calculator
Enter one side and get the perimeter of the rhombus: a side of 5 gives a perimeter of 20, because all four sides are equal.
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Rhombus side from diagonals calculator
Enter the two diagonals of a rhombus and get its side: diagonals of 6 and 8 give a side of 5, because the half-diagonals form a right triangle.
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Right triangle altitude
Enter the two legs of a right triangle and get the altitude from the right angle to the hypotenuse: legs of 3 and 4 give an altitude of 2.4, along with the…
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Right triangle from two legs calculator
Two legs are all it takes: legs of 3 and 4 give a hypotenuse of 5, an area of 6 and the acute angle opposite each leg, in degrees.
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Rose curve petal counter
Enter the coefficient k of a polar rose and get its petal count: k equal to 3 gives 3 petals, while k equal to 4 gives 8, because even values double the loops.
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Rotate a point around a center calculator
Turn a point around any pivot you choose: rotating (4, 2) by 90 degrees about (1, 1) lands it at (0, 4).
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Rotate a point around the origin calculator
Spin a point about the origin by any angle in degrees: (1, 0) turned 90 degrees becomes (0, 1). Positive angles go counterclockwise, the textbook convention…
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Sagitta calculator
Get the rise of a circular arc from its radius and half-angle: a radius of 10 with a half-angle of 30 degrees gives a sagitta of about 1.34, a chord of 10 and a…
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Scale a point from the origin calculator
Multiply a point's coordinates by a scale factor from the origin: (3, 4) scaled by 2 becomes (6, 8), and its distance from the origin grows from 5 to 10.
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Circular sector centroid calculator
Find where a pie-slice shape balances: for a quarter circle of radius 5, the centroid sits just over 3 units from the center, out along the bisector of the…
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Circular sector perimeter calculator
Measure the full outline of a pie slice: a radius of 5 at 90 degrees gives an arc of 5π/2 and a perimeter of 10 plus that arc, since both straight sides count.
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Sector radius from area calculator
Work backwards from a slice's area to its circle: an area of about 19.63 with a 90-degree angle gives a radius of 5, plus an arc of 5π/2 and the full perimeter.
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Circular segment chord calculator
Get the straight base of a circular segment from the radius and central angle: a radius of 10 at 90 degrees gives a chord of 10√2, together with the half-chord…
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Circular segment height calculator
Turn a radius and a chord into the height of the arc above it: a radius of 5 and a chord of 6 give a height of 1, because the chord sits 4 from the center.
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Do two segments intersect?
Check whether two finite segments really meet: the segments from (0, 0) to (4, 4) and from (0, 4) to (4, 0) cross at (2, 2), halfway along each.
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Segment trisection points calculator
Split a segment into three equal pieces in one step: from (0, 0) to (6, 0), the trisection points are (2, 0) and (4, 0), and the full length is 6.
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Semicircle area and perimeter calculator
Enter a radius and get both measures of a half disk: a radius of 1 gives an area of half π and a perimeter of π plus 2, because the flat diameter is part of the…
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Slope-intercept form calculator
Give two points and get the line's equation in slope-intercept form: (0, 3) and (2, 7) give a slope of 2 and an intercept of 3, so y equals 2x plus 3.
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Snub cube calculator
Enter one edge length and get the volume and total surface of a snub cube: an edge of 1 gives a volume of about 7.889 and a surface of about 19.856.
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Snub dodecahedron calculator
Enter one edge length and get the size of a snub dodecahedron: an edge of 1 gives a volume of about 37.6167 and a surface of about 55.2867, spread over 92…
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Sphere diameter from volume calculator
Start from the volume a sphere holds and get its width: the volume of a ball of radius 3 gives back a diameter of 6.
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Sphere great circle calculator
Give the radius of a sphere and size its largest circle: a radius of 5 gives a great circle of 10π around, an enclosed disk of π times 5 squared and a diameter…
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Sphere radius from surface area calculator
Work back from a sphere's outer skin to its size: a surface area of 4π gives a radius of 1 and a diameter of 2.
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Sphere surface area calculator
Give the radius of a ball and get its outer skin: a radius of 3 gives a diameter of 6 and a surface of four times π times 3 squared, the area to paint, plate or…
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Spherical cap surface area
Measure just the curved skin of a dome, the part you clad, coat or use for heat transfer: a cap 2 high on a sphere of radius 5 has a curved area of 20π.
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Spherical lune area calculator
Find the area of the slice of a sphere's surface between two meridians that meet at the poles: a 90° angle covers exactly one quarter of the sphere and 180°…
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Spherical wedge volume calculator
Find how much of a solid ball lies between two half-planes that share a diameter: on a sphere of radius 5, a 90° opening holds 130.8996938996 cubic units, one…
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Spindle torus calculator
Turn two radii into the volume and surface of a spindle torus, the doughnut whose tube is so fat that it crosses itself: a major radius of 1 with a minor radius…
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Square area calculator
Square one side length to get the area of any square: a side of 5 gives 25 and a side of 12 gives 144, ready for tiles, paint or homework.
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Square diagonal calculator
Multiply the side of a square by √2 and get its corner-to-corner diagonal: a side of 5 gives 7.071067811865 and a side of 1 gives 1.414213562373.
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Square side from area calculator
Find the side of a square from its area by taking the square root: an area of 25 gives a side of 5, the length to mark out when a room, patio or garden bed…
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Square side from diagonal calculator
Divide a square's diagonal by √2 to get its side: a diagonal of 14.142135623731 gives a side of 10, and a diagonal of 10 gives about 7.071067811865.
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Stellated octahedron calculator
Enter one edge and get the volume and outer surface of the stella octangula, Kepler's star of two interlocking tetrahedra: an edge of 1 gives a volume of…
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Stewart's theorem calculator
Find the length of the segment from a triangle's vertex to any point on the opposite side, from the three sides and the two pieces of the base: sides 7, 5 and 6…
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Superellipse area calculator
Get the exact area inside a superellipse, from diamond to ellipse to squircle: semi-axes 2 and 1 with exponent 2 give the ellipse area 2π, and larger exponents…
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Tangent length from external point
Find how long the tangent is from a point outside a circle to the spot where it touches: a radius of 3 and a distance of 5 from the centre give a tangent of 4.
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Tetrahedron height calculator
Get the vertical height of a regular tetrahedron from its edge alone, the straight drop from one vertex to the opposite face: an edge of 6 gives a height of…
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