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Right Triangle Calculator — Quick & Accurate Online Calculator & Guide

Solve right triangles using the Pythagorean theorem and SOH CAH TOA trigonometry. Find sides, angles, area, and perimeter with a dynamic SVG triangle and.

✓ Formula verified: January 2026

Right Triangle

Results below

Enter Values

Hypotenuse (c)
5

Triangle Area

6

Perimeter

12

Angle A (opposite leg a)

36.8699°

Angle B (opposite leg b)

53.1301°

SOH Step

sin(α) = opposite/hypotenuse = a/c = 3/5 = 0.6000 → α = 36.87°

CAH Step

cos(α) = adjacent/hypotenuse = b/c = 4/5 = 0.8000 → α = 36.87°

TOA Step

tan(α) = opposite/adjacent = a/b = 3/4 = 0.7500 → α = 36.87°

What if your leg a changes? 2.7 → 4.8259714 · 3 → 5 · 3.3 → 5.18555686

Scenario Comparison

Conservative (5%)
$16,470.09
$6,470.09 interest
Your scenario (7%)
$20,096.61
$10,096.61 interest
Aggressive (10%)
$27,070.41
$17,070.41 interest
High-risk (14%)
$40,224.71
$30,224.71 interest
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Right Triangle & Step-by-Step Proof
cba

Step-by-Step Proof

c² = a² + b² = 3² + 4² = 9 + 16 = 25 c = √(25) = 5.0000

Isolate the variable: c = √(a² + b²)

SOH CAH TOA — Finding Angles

SOH sin(α) = Opposite / Hypotenuse = a / c = 3 / 5 = 0.6000

CAH cos(α) = Adjacent / Hypotenuse = b / c = 4 / 5 = 0.8000

TOA tan(α) = Opposite / Adjacent = a / b = 3 / 4 = 0.7500

α = sin⁻¹(0.6000) = 36.8699°  |  β = 90° − α = 53.1301°

Leg a

3

Leg b

4

Hypotenuse c

5

Pythagorean Theorem

a² + b² = c²

Hypotenuse

c = √(a² + b²)

Leg a

a = √(c² − b²)

Leg b

b = √(c² − a²)

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