Find the exact value of the expression cos 2 pi9 pi18 12 1

Find the exact value of the expression. cos (2 pi/9 - pi/18) 1/2 1 squareroot 3/2 Complete the identity. Cos (3 pi/2 - x) = ? -cos x -sin x sin x Find the exact value by using a sum of difference identity. Cos (135 degree + 30 degree) - squareroot 2 (squareroot 3 + 1)/4 - squareroot 2(squareroot 3 - 1)/4 squareroot 2(squareroot 3 - 1)/4 Complete the identity. Sin (x - 3 pi/2) = ? cos x -sin x sin x SHORT ANSWER. Write the word or phrase that best completes each statement or answer Verify the identity. Cos(alpha + beta)/cos alpha sin beta = cot beta - tan alpha MULTIPLE Choice. Choose the one alternative that best completes the statement or answer Describe the graph using another equation. y = sin (pi - x)

Solution

Given

cos[(2pi/9) - (pi/18)]

= cos[40 - 10]

= cos30

= sqrt(3)/2

Option C) is correct.