Area

Calculate area and perimeter for common 2D shapes including rectangle, square, triangle, circle, trapezoid, parallelogram, rhombus, ellipse, annulus, sector, and regular polygon.

Calculate triangle area from base and height, three sides, two sides and an included angle, angles and a side, coordinates, right-triangle legs, or circle radii with three sides.

Calculate triangle area from three side lengths using Heron's formula, with semiperimeter, triangle inequality checks, heights, angles, and incircle/circumcircle radii.

Calculate triangle area from base and perpendicular height, or solve the reverse problem for base or height from a known area.

Calculate triangle area from two sides and the included angle, then recover the third side, perimeter, angles, heights, and circle radii.

Calculate right triangle area from two legs, leg and hypotenuse, leg and acute angle, hypotenuse and acute angle, or leg and altitude to the hypotenuse.

Calculate isosceles triangle area from base and equal side, base and height, equal side and height, apex angle, or base angle, with perimeter, height, angles, inradius, and circumradius.

Calculate equilateral triangle area from side, height, perimeter, known area, inradius, or circumradius, with side length and all related values recovered automatically.

Calculate square area from side length, diagonal, perimeter, known area, inradius, or circumradius, with reverse calculations for all related square measurements.

Calculate rectangle area from length and width, or recover rectangle measurements from side plus diagonal, area, perimeter, diagonal angle, or perimeter plus area.

Calculate parallelogram area from base and height, two sides with the included angle, diagonals with their angle, or two sides and one diagonal.

Calculate rhombus area from diagonals, side and height, side and angle, or side and one diagonal, with perimeter, height, angles, diagonals, and inradius.

Calculate trapezoid area from bases and height, midsegment and height, four sides, isosceles trapezoid sides, right trapezoid dimensions, or diagonals and angle.

Calculate circle area from radius, diameter, circumference, or known area, then recover radius, diameter, circumference, and area.

Calculate circle sector area, circular segment area, arc length, chord length, sagitta, and perimeter from radius, angle, arc, chord, or segment height.

Calculate ellipse area from semi-major and semi-minor axes, with Ramanujan perimeter estimate, eccentricity, focal distance, and a visual sketch.

Calculate the area of a regular polygon from number of sides plus side length, apothem, circumradius, or known area, with perimeter, angles, and radii.

Solve a regular polygon from number of sides plus side length, inradius, circumradius, or area, including perimeter, area, angles, apothem, and diagonals.