A familiar situation
Estimate the area and missing side of a triangular garden when two edges and their angle are known.
How to use this calculator
- Enter side a, side b, included angle.
- Select Calculate to see the answer and its breakdown.
- Keep a scenario, change an input and compare the results.
Use consistent units and check the assumptions below before applying the result.
How triangle is calculated
With sides a and b and included angle C, area = ab sin(C)/2 and c = √(a²+b²−2ab cos(C)). The entered angle is in degrees. Sides 5 and 7 with an included 60° angle give area about 15.16 square units and third side √39 ≈ 6.245.
Area=ab sin(C)/2; c=√(a²+b²−2ab cos(C)).Sides 5 and 7 with an included 60° angle give area about 15.16 square units and third side √39 ≈ 6.245.
Assumptions & useful context
The result depends on the values you enter and the method described above. Displayed numbers may be rounded; calculations use the unrounded values. Check that this model matches your situation before relying on it.
Frequently asked questions
Does the angle have to be between 0° and 180°?
Yes; a triangle’s interior angle must be strictly between those bounds.
What units does the area use?
Squared versions of the side unit, so centimetres produce square centimetres.