Question

If cos A= 2/ 5 = , find the value of 4 + 4 tan2 A

Answer 1

Hi there!

Given,
cos A = 2/5

4+4tan × tanA

4+4tan²A

cos A = 2/5

1/sec A = 2/5 

sec A = 5/2

4 + 4 tan²A

4( 1 + tan²A)

4 ( sec²A)

4(5/2)²

4 × 25 /4 

25

Cheers!