Question

Given that sinx=3/5 where x is an acute angle for cosx

Answer 1

The correct question is
Given that sinx=3/5 where x is an acute angle, what is cosx and tanx?

we  know that

since x is acute   0<x<π/2
then the trigonometric rations will be positive

sin ²x+cos²x=1------------> cos²x=1-sin²x------->  cos²x=1-(3/5)²----> 1-(9/25)
cos²x=16/25----------> cos x=4/5

the answer part A) is 
cos x=4/5

tan x=sin x/cos x
so
tan x=(3/5)/(4/5)---------> tan x=3/4

the answer part B) is 
tan x=3/4