Right Triangle Calculator (Trigonometry)
By Santaji GadepatilinUpdated October 27, 2026
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Type in any field to change it. Press × on a value to calculate that field instead.
Side opposite A (a) (m) vs Angle A (°) — other inputs held at your current values.
How to use this calculator
Enter one angle and one side, or two sides. All remaining sides and angles are calculated. Angles can be entered in degrees or radians.
Formulas (SOH CAH TOA)
sin A = a ÷ c cos A = b ÷ c tan A = a ÷ b
A + B = 90°
Worked example
A hypotenuse of 10 m at angle A = 30°:
- a = 10 × sin 30° = 5 m
- b = 10 × cos 30° = 8.66 m
- B = 90° − 30° = 60°
Ladder check: a 6 m ladder at 75° (the recommended safe angle) reaches 6 × sin 75° = 5.80 m high with its foot 6 × cos 75° = 1.55 m from the wall.
Special angles
| Angle | sin | cos | tan |
|---|---|---|---|
| 0° | 0 | 1 | 0 |
| 30° | 0.5 | 0.866 | 0.577 |
| 45° | 0.707 | 0.707 | 1 |
| 60° | 0.866 | 0.5 | 1.732 |
| 90° | 1 | 0 | undefined |
Frequently asked questions
What does SOH CAH TOA mean?
A memory aid — Sine = Opposite/Hypotenuse, Cosine = Adjacent/Hypotenuse, Tangent = Opposite/Adjacent.
How do I find an angle from two sides?
Press × on Angle A, then type two sides. The angle is found with the inverse trig functions.
Do the angles always add up to 90°?
The two acute angles do. With the right angle, all three add up to 180°.