a12 b12 and c12 What is angle A B and CSolutiona 12 b12 c1

a=12, b=12, and c=12
What is angle A, B, and C?

a =12 ; b=12 ; c=12

Use the cosine rule:

c^2 = a^2 +b^2 -2abcosC

cosC = (a^2 +b^2 -c^2)/2ab

= (12^2 +12^2 -12^2)/2*12*12

= (144)/2*12*!2

= 1/2

C = cos^-1(1/2) = pi/3

Sinc all the sides are equal so, its an equiltaeral triangle:

A= B = C = pi/3 (rad) = 60 deg