Evaluate expression without a calculator Write answer in rad

Solution

sin^-1(-1/2) =y

range of sin^-1(x) : -pi/2<=y<=pi/2

So, value of y would be less than pi/2and its is -ve so it should be between -pi/2 and 0

y = sin^-1(-1/2)

siny = -1/2

y = -pi/6 radians