Question

If sin(x) = 1/3 and sec(y) = 25/24 , where x and y lie between 0 and π/2, evaluate the expression using trigonometric identities. (Enter an exact answer.) sin(x − y)

Answer 1

sin(x-y) = (24-14*sqrt(2))/75 Write down what you know sin(x) = 1/3 sec(y) = 25/24 cos(y) = 1/sec(y) = 24/25 cos(x) = sqrt(1-sin(x)^2) = sqrt(1-1/9) = sqrt(8/9) = 2*sqrt(2)/3 sin(y) = sqrt(1-cos(y)^2) = sqrt(1-576/625) = sqrt(49/625) = 7/25 We now know the sin and cos of both x and y. Now to get the sin of x-y. sin(x-y) = sin(x)cos(y) - cos(x)sin(y) Substitute the known values for sin and cos of x and y, then evaluate and simplify sin(x-y) = (1/3)(24/25) - (2*sqrt(2)/3)(7/25) sin(x-y) = 24/75 - 14*sqrt(2)/75 sin(x-y) = (24-14*sqrt(2))/75