Suppose, α is the angle between hypotenuse and its adjacent side. Then, the measure of angle α is given by;
α = sin-1 (opposite side of α/hypotenuse)
Where sin-1 represents the sine inverse function.
Let α is an angle equal to Sin-1 (1/2)
α = sin-1(1/2)
We know that, sin 30 degrees = 1/2
Therefore, α = sin-1 (sin 30) = 30 degrees= ∏/6
Sin-1 (1/2)= ∏/6