# Oblique Triangle

## Oblique triangle equations

An oblique triangle is any triangle that is not a right angled triangle.

### Triangle Three Known Values - Length and Angle Calculator

Calculate the unknown lengths and angles in a triangle. Add three known values - leave the rest of the inputs blank.

**Note!** - the calculator is based on the same value combinations used in the equations below. Other value combinations will not work - most triangles with three known values can be adapted to these equations. The calculator is quite simple. With strange results - **check your input values**.

*Angle A (degrees)*

* Angle B (degrees)*

* Angle C (degrees)*

* Length a (m, mm, ft, in ..)*

* Length b (m, mm, ft, in ..)*

* Length c (m, mm, ft, in ..)*

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Area* (m ^{2}, mm^{2}, ft^{2}, in^{2} .....)*:

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### A, B and a is known, calculate

*b = a sin(B) / sin(A) (1a)*

* C = 180 ^{o} - (A + B) (1b)*

* c = a sin(C) / sin(A) (1c)*

### A, a and b is known, calculate

*sin(B) = b sin(A) / a (2a)*

* C = 180 ^{o} - (A + B) (2b)*

* c = a sin(C) / sin(A) (2c)*

### a, b and C is known, calculate

*tan(A) = a sin(C) / (b - a cos(C)) (3a)*

*B= 180 ^{o} - (A + C) (3b)*

* c = a sin(C) / sin(A) (3c)*

### a, b and c is known, calculate

*cos(A) = (b ^{2} + c^{2} - a^{2}) / (2 b c) (4a)*

*cos(B)= (a ^{2} + c^{2} - b^{2}) / (2 a c) (4b)*

*C = 180 ^{o} - (A + B) (4c)*

### a, b, c, A, B and C is known, calculate area

*s = (a + b + c) / 2 (5a)*

*area = (s (s - a) (s- b) (s - c)) ^{1/2} (5b)*

*area = b c sin(A) / 2 (5c)*

*area = a ^{2} sin(B) sin(C) / (2 sin(A)) (5d)*