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.
AAA triangle calculator
Angles of 50, 60 and 70 degrees with a side of 8 opposite the 50° angle give the other sides at about 9 and just under 10.
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Angle between two lines calculator
Enter two slopes and get the acute angle between the lines: slopes 1 and 0 meet at 45°, while 2 and −1/2 are perpendicular at 90°.
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Annulus sector area calculator
A 90° slice of a ring with outer radius 10 and inner radius 4 covers 65.973445725386 square units, a quarter of the full ring.
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Annulus width from area calculator
A ring with an area of 3π and an inner radius of 1 has an outer radius of 2, so its width is 1. Start from a measured or budgeted area and get the outer edge…
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N-antiprism calculator
A square antiprism with every edge 1 has a volume of about 0.957 and a surface area of about 5.464 square units.
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Astroid area and perimeter calculator
Enter the distance a from the centre to any cusp and get the astroid's exact area, (3/8)πa², and its perimeter, 6a: a radius of 1 gives a perimeter of 6 and an…
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N-gonal bipyramid calculator
Enter how many sides the middle polygon has, its edge and the height of one tip, and get the bipyramid's volume and surface: a square one with edge 2 and height…
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Bretschneider formula calculator
Get the area of any four-sided shape from its four sides and a pair of opposite angles: four sides of 2 with right opposite angles give an area of 4.
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Chebyshev distance calculator
Measure the chessboard distance between two points, the larger of the horizontal and vertical gaps: from (0, 0) to (3, 4) it is 4, not the 5 a ruler would show.
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Circle area from radius calculator
Type a radius and get the circle's area, πr², together with its diameter and circumference: double the radius and the area grows four times.
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Circle circumference calculator
Enter a radius and get the distance around the circle, 2πr: a radius of 5 gives 10π, about 31.4159, and a unit circle gives 2π.
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Circle around a square calculator
Get the radius of the circle that passes through all four corners of a square: it is the side times √2/2, so a side of 1 gives about 0.7071.
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Circle diameter from circumference calculator
Measure the distance around a circle and get how wide it is: the diameter is the circumference divided by π, so a circumference of 2π gives a diameter of 2.
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Circle from center and point
Give the center and one point on the circle and get its radius and equation: a center at the origin and the point (3, 4) give a radius of 5 and x² + y² = 25.
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Circle radius from area calculator
Enter the area of a circle and get its radius, the square root of the area divided by π: an area of π gives a radius of 1 and a diameter of 2.
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Triangle circumcircle area
Enter a triangle's three sides and get the area of the circle that passes through its corners: sides 3, 4 and 5 give a circumradius of 2.5 and a circle area of…
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Collinear points checker
Check whether three points lie on one straight line: (0, 0), (1, 1) and (2, 2) do, because the triangle they form has zero area.
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Cone apex angle calculator
Get the full opening angle of a cone, twice arctan(r/h), from its base radius and its height; radius 3 and height 4 give about 73.7397952917°.
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Cone lateral surface area
Get the area of a cone's sloping side from its base radius and slant height with π r l: a radius of 3 and a slant height of 5 give exactly 15π.
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Cone slant height calculator
Find the slant height of a cone, the straight edge from the base rim up to the tip, from its radius and height; radius 3 and height 4 give exactly 5.
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Conic eccentricity calculator
Find how stretched a conic is: an ellipse with semi-axes 5 and 4 has an eccentricity of 0.6 and its focus 3 from the center.
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Coplanarity checker
Check whether four points in space lie on one flat plane: (0, 0, 0), (1, 0, 0), (0, 1, 0) and (1, 1, 0) do, while lifting the last one to (1, 1, 1) makes a…
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Sphere circumscribed about a cube calculator
Find the smallest sphere that encloses a cube, passing through all eight corners: its radius is the edge times √3/2, so an edge of 1 gives about 0.866.
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Cube space diagonal calculator
Find the longest straight line inside a cube, from one corner to the opposite one: it is the edge times √3, so an edge of 2 gives about 3.464.
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Cube surface area from volume calculator
Turn a cube's volume into its outer surface area: a volume of 8 gives an edge of 2 and a surface of 24, since the edge is the cube root and the surface is six…
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Cuboid space diagonal calculator
Find the longest straight line inside a box, from one corner to the opposite one: a box of 2 by 3 by 6 has a space diagonal of exactly 7.
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Cuboid surface area calculator
Get the total outer area of a rectangular box from its three edges: a box of 3 by 4 by 5 has faces of 12, 15 and 20 and a total surface of 94.
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Brahmagupta formula calculator
Enter the four sides of a quadrilateral inscribed in a circle and get its area: sides 3, 4, 3 and 4 give a semiperimeter of 7 and an area of 12.
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Ptolemy theorem calculator
Ptolemy's theorem from four sides: for a cyclic quadrilateral with sides 3, 4, 3 and 4, the diagonals multiply to 25, shown as 9 plus 16 from the opposite pairs…
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Cycloid arc length and area calculator
Give the radius of the rolling circle and get one full cycloid arch: a radius of 1 gives an arch length of 8 and an area of 3π, three times the area of the…
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Cylinder height from volume calculator
Get the missing height of a right cylinder from its volume and the radius of its base: with radius 3, a volume equal to ten times the base area means a height…
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Cylinder lateral surface area
Get the area of a cylinder's curved wall alone: radius 3 and height 5 give 30π, the label or insulation you would wrap around it, without the two ends.
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Decagon area calculator
Enter one side of a regular ten-sided figure and get its area: a side of 5 gives about 192.355, with a perimeter of 50 plus the apothem and outer radius for the…
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Decagon area from apothem
Turn the apothem of a regular decagon into its area: an apothem of 1 gives ten times tan(π/10) square units, and any other apothem scales that by its square.
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Decagon circumradius calculator
Get the radius of the circle through all ten corners of a regular decagon from its side length, so a side of 2 gives a circumradius of about 3.2360679775.
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Decagon perimeter calculator
Multiply one side by ten and you have the full boundary of a regular decagon: a side of 6 gives a perimeter of 60, the trim, rope or fence you need to go all…
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Decagonal prism calculator
Enter the base side and height of a regular decagonal prism and get its capacity and surfaces: side 2 and height 5 give a base perimeter of 20 and a wall area…
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Distance between two points in 3D
Give two points in space and get the straight line between them: from (0, 0, 0) to (3, 4, 12) is exactly 13, with the differences along x, y and z listed so no…
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Dodecagon area calculator
Give the side of a regular dodecagon and get the area it encloses: a side of 1 covers about 11.196 square units, three times (2 + √3) the side squared, with…
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Dodecagon area from apothem
Measure from the centre of a regular twelve-sided shape to the middle of one side, and that apothem gives the area: for an apothem of 1 it is twelve times…
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Dodecagon circumradius calculator
Enter the side of a regular dodecagon and get the radius of the circle through its twelve corners: a side of 5 gives about 9.65926, and a side of 1 about…
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Dodecagon perimeter calculator
Twelve equal sides make the sum easy: a regular dodecagon with a side of 6 has a perimeter of 72, the length of frame, trim or rope that goes once round it.
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Dodecahedron inradius calculator
Enter the edge of a regular dodecahedron and get the radius of the largest sphere that fits inside it: an edge of 2 gives an inradius of about 2.2270327288…
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Dodecahedron midradius calculator
Enter the edge of a regular dodecahedron and get the radius of the sphere that touches every edge at its midpoint: an edge of 2 gives a midradius of about…
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Dodecahedron surface area calculator
Enter the edge of a regular dodecahedron and get the area of its whole outer skin: an edge of 2 gives twelve faces of about 6.881909602356 each, about…
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Ellipse area calculator
Multiply pi by the two semi-axes and you have the area of an ellipse: semi-axes of 5 and 3 enclose about 47.123889803847 square units.
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Ellipse directrix calculator
Enter the two semi-axes of an ellipse and get the distance from the centre to each directrix line: semi-axes of 5 and 3 give a focus at 4, an eccentricity of…
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Ellipse foci calculator
Enter the semi-major and semi-minor axes of an ellipse and get its two foci: axes of 5 and 3 put them at (4, 0) and (−4, 0), 8 apart, with an eccentricity of…
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Ellipse latus rectum calculator
Enter the two semi-axes of an ellipse and get the chord through a focus: semi-axes of 5 and 3 give a semi-latus rectum of 1.8 and a full latus rectum of 3.6…
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Ellipse perimeter calculator
Get the distance around an ellipse from its two semi-axes with Ramanujan's first approximation: semi-axes of 5 and 3 give about 25.526986393759, using one…
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Ellipse circumference
Give the two semi-axes of an ellipse and get its circumference from Ramanujan's second formula: semi-axes of 5 and 3 give about 25.53, with a shape value h of…
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Ellipse segment area calculator
Enter the two semi-axes of an ellipse and where a vertical line cuts it, and get the smaller piece: semi-axes of 5 and 3 cut 2 from the centre leave a segment…
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Ellipse general to standard form calculator
Enter the six coefficients of a general second-degree equation and get the ellipse in standard form: x² + 4y² − 4 = 0 becomes an ellipse centred at the origin…
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Ellipsoid semi-axis from volume calculator
Recover the missing semi-axis of an ellipsoid from its volume — a volume of 8π with semi-axes 3 and 2 leaves a third semi-axis of 1.
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Ellipsoid surface area calculator
Get the skin area of an ellipsoid from its three semi-axes: 3, 2 and 1 give close to 49 square units, while three equal semi-axes of 5 give exactly 100π.
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Equilateral triangle area from side calculator
Enter one side and get the equilateral triangle's area, height and perimeter at once: side 6 gives an area of 9√3, about 15.5885, a height of about 5.1961 and a…
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External tangent length calculator
Get the length of the outer common tangent between two separate circles: radii 5 and 3 with centres 10 apart give 4√6, just under 10.
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Foot of perpendicular calculator
Find the point on a line closest to a given point: a perpendicular dropped from the origin onto the line 3x + 4y − 5 = 0 lands at (0.6, 0.8), at distance 1.
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Conical frustum slant height calculator
Get the slant height of a truncated cone from its two radii and height, so radii 3 and 4 with a height of 5 give √26, about 5.099.
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Hendecagon apothem calculator
Turn the measured side of a regular 11-sided polygon into its apothem, the distance from the centre to the middle of each edge, so side 1 gives 1 ÷…
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