Law of sines — Precalculus, what it means and where it is taught
asin A = bsin B = csin C.
Taught in Precalculus.
Where it is taught
Practise this idea
2 questions in the course bank use Law of sines, in The Law of Sines & Cosines.
Problem 1
Two angles and one side are known. Which rule applies?
- Law of sines
- Law of cosines
- Pythagoras
- Neither
Worked answer
Law of sines
The third angle follows, giving a complete pair
Problem 2
All three sides are known and no angles. Which rule applies?
- Law of cosines
- Law of sines
- Pythagoras
- Neither
Worked answer
Law of cosines
No angle is known, so the sine rule cannot start