MAth need help?

Question

can anyone tell the cosine law.

The sine law is
sin a\a=sin b\b=sin c\c

Pls help, thanks

Answer 1

The sine law is (more clearly):
A/(sin a) = B/(sin b) = C/(sin c)
Always put parentheses in the appropriate places, otherwise it looks like you are dividing a/a, b/b, c/c, which equals 1.

The law of cosines looks a lot like the Pythagorean theorem (and in fact, it is simply a generalization of the Pythagorean theorem):
A2 = B2 + C2 - 2BC cos a
B2 = A2 + C2 - 2AC cos b
C2 = A2 + B2 - 2AB cos c

Answer 2

There are two.

1. a= b* cosC +c* cos B (A,B,C=angles)
b= c* cosA + a*cos C
c= a* cosB + b* cos A

2. a^2 = b^2+ c^2 -2 *b*c* cos A
b^2 = a^2 + c^2 - 2ac cos B
c^2 = a^2 + b^2 -2ab cos C

But you use 2. a lot more than 1.