13. (cosx) (tanx + sinxcotx) = sinx + cos2x secx+1 15. cotax - cos2x = cos?xcot?x tanx 1-cosx Use a sum or difference identity to find an exact value. 16. sin15" 17. tan 12 Write the expression as the sine, cosine, or tangent of an angle. 18. sin42 cos17 - cos42'sin17 19. tan()-tan() 1+tan()tan(=)Find the exact value on the interval [0, 27). 24. 2cos2x = - V2 25. Given the identity: tanx + cotx = secxcsex. Is x = ; a solution to the identity? Give a reason for your answer.Find all solutions to the equation in the interval [0,27) without a calculator. 7. Vatanxcosx - tanx = 0 8. 2sin x + 3sinx + 1 = 0 Find all solutions to the equation in the interval [0,27) with a calculator. 9. cosx = .75 10. sin2x = 0.4 Prove the identity. 11. Singa = sinxcosx 12. cos x-1= - tanxsinx 2 cosxProve the identity. 20. cos (x - ") = sinx 21. sin(3x) = (sinx)(3 - 4sin2x) Find all solutions to the equation in the interval [0,2x) without a calculator. 22. cos2x = sinx 23. sin2x = 2sinxSHOW ALL WORK! Evaluate without using a calculator. 1. Find seco and csco if tand = 3 and cose > 0. Use identities to find the value of the expression. 2. If cosa = and i