Cosine Rule (and friends)

Question 1

Cosine Rule (a²)

Answer 1

a² = b²+c²-2bccos(a)

Question 2

Cosine Rule (cos(A))

Answer 2

cos(A) = (b²+c²-a²)/2bcS

Question 3

Sine Rule (a)

Answer 3

a/sin(A) = b/sin(B) = c/sin(C)

Question 4

Sine Rule (sin(A))

Answer 4

sin(A)/a = sin(B)/b = sin(C)/c