Question

Using the triangle below, answer the following questions.

Answer 1

Step-by-step explanation:

Answer(1):

Law of Cosines.

Answer(2):

since side "c" is missing so we will write formula used for side "c"

$c^2=a^2+b^2-2ab\cdot\cos\left(C\right)$

Answer(3):

First lets write both sine and cosine formulas:

Check the attached picture for the list of formulas:

From given picture we see that two angles A and B are missing. Also 1 side "c" is missing.

Sine formula uses two angles while cosine formula uses only one angles.

Hence cosine formula will be best choice to find the missing values.