Use the Law of Cosines to solve the triangle. Round your answers to two decimal places

Question

.

a = 52,  b = 21,  c = 72

A	=	°
B	=	°
C	=	°

Answer 1

Law of Cosines:

c^2 = a^2 + b^2 - 2 a b cos C

Use the above equation to determine angle C.

Then use law of sines to determine angle B

sin B = sin C

------- -------

b c

Then angle A = 180 - (angle B + angle C)

Answer 2

The law of cosines states that and any of the three sides can be assigned to any of the variables. For your case because they are already labeled, it is easiest to leave the variables as is. Therefore, the equation would be

72² = 52² + 21² - 2*52*21*cos(c)

you want to rearrange the formula to isolate the variable, which would get you

cos(c) = -0.9336

therefore, angle c = 159.00°

Repeat the same procedure with the other two variables, to get angle a = 15.00° and angle b = 6.00°

Remember to make sure that the angles add up to 180°!