Given cosθ=3/7 and 0≤θ≤π/2 find sinθ and tanθ

Answer 1

sin^2 T = 1 - cos^2 T
sin^2 T = 1 - 9/49

sin^2 T = 40/49
sin T = (2/7) sqrt 10

and tan T = sin T/cos T

Answer 2

or, just draw the triangle and label the sides. The missing side is √(49-9) = √40

Then you can read off all the trig functions just by looking at the sides and using the proper ones.