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Mathematics

Right Triangle Calculator

Pythagorean Theorem — a² + b² = c²

Variable Legend

a= legb= other legc= hypotenuseA= areaα,β= acute angles

Pythagorean theorem

Relationship between the three sides.

Area

Half the product of the two legs.

Trigonometric ratios

SOH-CAH-TOA for angle α (opposite side a).

sin α
cos α
tan α

Angle from sides

Find an angle when all sides are known.

Angle α
Angle β
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Pro Tip

To check if a triangle is a right triangle: compute a²+b² and c². If equal, it's a right triangle. Also: if a triangle's longest side satisfies c²>a²+b², it's obtuse; if c²<a²+b², it's acute.

Difficulty:Intermediate

Did you know?

The 3-4-5 right triangle was known to ancient Egyptians, who used knotted ropes with 12 equal spaces to create right angles for surveying land after Nile floods. This "rope-stretching" method is one of the earliest practical applications of the Pythagorean theorem.

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Reviewed May 2026
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