Question

cosA=2/5, Find the valu of 4+4tan square A.

Answer 1

Given that =cos A= 2/5
and 4+4tan² A=?............i
now, solving equation i , we get
4(1+tan²A) =4sec²A. {1+tan²x=sec²x}
now 1/cos A =secA
so, sec A =5/2
and, sec²A= (5/2)² =25/4
and 4sec²A=4*25/4=25
and 4+4tan²A =4sec²A=25
this is the required answer

Answer 2

given that cosa=2/5
then tan A= √21/2
4+4tan square A=4+4*(√21/4)whole square
=4+4*21/16
=4+21/4
=37/4