If 0 < x < π/2, then both sin(x) and cos(x) are positive.
From the Pythagorean identity, we then have
cos²(x) + sin²(x) = 1
⇒ cos(x) = + √(1 - sin²(x)) and sin(x) = + √(1 - cos²(x))
Then
√(1 - cos²(x))/sin(x) = sin(x)/sin(x) = 1
and
√(1 - sin²(x))/cos(x) = cos(x)/cos(x) = 1
so that the overall expression reduces to
1 - 1 = 0
