In triangle abc, a = 9, c = 5, and angle b = 120°. find the measure of angle a to the nearest degree. show your work.

Angle A = 39°

Step-by-step explanation:

We are given that there is a triangle ABC where a = 9, c = 5 and angle B = 120° and we are to find the measure of angle A.

But first we need to find the side b using the law of cosine:

Now finding angle A using law of cosine:

Therefore, the measure of angle A = 39°.

correct answer:

b.(19,-2)

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12