Triangle calculators
20 calculators 30-60-90 Triangle Calculator Solve a 30-60-90 triangle from any known value: short leg, long leg, hypotenuse, height, area, or perimeter. Get sides, altitude, inradius, circumradius, and area instantly.
Open 45-45-90 Triangle Calculator Solve a 45-45-90 triangle from any known value: leg, hypotenuse, altitude, area, or perimeter. Get all sides, inradius, circumradius, and step-by-step work.
Open Equilateral Triangle Calculator Solve any equilateral triangle property: enter the side, height, area, perimeter, inradius, or circumradius and get all six values instantly with step-by-step work.
Open Hypotenuse Calculator Find the hypotenuse from two legs, one leg plus an angle, or a special triangle. Also outputs both angles, altitude, perimeter and area instantly.
Open Isosceles Triangle Calculator Calculate area, height, perimeter, base angles, apex angle, inradius, and circumradius of an isosceles triangle. Choose from 5 solve modes.
Open Pythagorean Theorem Calculator Solve any right triangle: enter any two of three sides (a, b, c) to find the missing side, both angles, area, perimeter, and altitude. Unit switching included.
Open Right Triangle Calculator Solve any right triangle from any two values. Get sides, angles, area, perimeter, semiperimeter, all three altitudes, inradius, and circumradius instantly.
Open Triangle Area Calculator Find any triangle's area from base-height, three sides (Heron's), SAS, ASA, or equilateral shortcut. Switch metric or imperial units and see every step.
Open Area of a Right Triangle Calculator Calculate the area of a right triangle from two legs, a leg and hypotenuse, a leg and angle, or hypotenuse and angle. Includes a full worked solution.
Open Circumscribed Circle Calculator Find the circumscribed circle radius, diameter, circumference and area for any triangle. Enter three side lengths in metric or imperial units and see every step.
Open Classifying Triangles Calculator Classify any triangle by sides (equilateral, isosceles, scalene) and angles (acute, right, obtuse). Get angles, area, perimeter, inradius and circumradius instantly.
Open Heron's Formula Calculator Calculate the area of any triangle from its three sides using Heron's formula. Shows altitudes, interior angles, inradius, and circumradius with step-by-step working.
Open Perimeter of a Triangle Calculator Calculate the perimeter of any triangle using three sides (SSS), two sides and an angle (SAS), or one side and two angles (ASA). Shows all steps and the semi-perimeter.
Open Pythagorean Triples Calculator Check if three integers form a Pythagorean triple or generate one with Euclid's formula. Finds primitives, scaling factors, area, perimeter, and step-by-step math.
Open Right Triangle Side and Angle Calculator Solve any right triangle instantly. Enter two known values to find all sides, both acute angles, altitude, area, and perimeter with step-by-step working.
Open Similar Triangles Calculator Check if two triangles are similar by SSS, SAS, or AA. Find any missing side, scale factor, area ratio, and perimeter ratio with full step-by-step working.
Open Special Right Triangles Calculator Solve any special right triangle: 45-45-90, 30-60-90, 3-4-5, and more. Enter one side to get all sides, angles, area, and perimeter instantly with full steps.
Open Triangle Angle Calculator Solve any triangle. Enter any 3 known values (sides and angles) to get all missing angles, sides, area, perimeter, inradius, and circumradius with steps.
Open Triangle Height Calculator Calculate the height (altitude) of any triangle. Choose from four methods: three sides, area and base, two sides and angle, or equilateral formula. All three altitudes shown.
Open Triangle Inequality Theorem Calculator Check whether three side lengths form a valid triangle. See which inequalities pass or fail, find the valid range for any missing side, and get a step-by-step proof.
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