Question

What is the measure of angle A please help I’ll give you BRAINLIEST

Answer 1

Answer:

$A = 38^\circ$

Step-by-step explanation:

Given

$a = 5$

$b = 3$

$c = 7$

Required

Determine the measure of A

To do this, we apply cosine law as follows:

$a^2 = b^2 + c^2 -2bcCosA$

$5^2 = 3^2 + 7^2 -2*3*7*CosA$

$25 = 9 +49 -42*CosA$

Collect Like Terms

$42*CosA = 9 +49 -25$

$42*CosA = 33$

Make CosA the subject

$CosA = 33/42$

$CosA = 0.7857$

Take arccos of both sides

$A = cos^{-1}(0.7857)$

$A = 38^\circ$