It whould be -1.5 for and 0.5
Can i please get an image and i will be glad to help :)
We know that
sin²x+cos²x=1
so
clear cos x
cos x=(+/-)√[1-sin²x]
in this problem
<span>Angle 0 is in quadrant 1 -----> cos o and sin o are positive
</span>sin o=2/5
cos x=√[1-(2/5)²]----> cos o=√[1-4/25]----> cos o=√[21/25]---> cos o=√21/5
the answer is
cos o=√21/5