Please help me solve problems 90,91, and 93. I already did 92 so you don't have to solve it.

verify the following trigonometric identities. Intermediate steps may involve complex 5-90. fractions. a. csc2 x + sec? x - tan x - cot2 x = 2 sec x - 1 = sec x b. 1 - cos x log2 A + log2 B = 4 Solve the system: 5-91. log 3 A - log3 B = 2 5-92. Mr. Powers determines his sons allowance based on the following situations: The amount of money they receive in a week is directly proportional to the number of hours of work they have done in the yard and inversely proportional to 5 - GPA where GPA is the grade point average from the last report card. Clark received $14.40 since week. his last report card had a GPA of 3.5, and he worked 10 hours in the yard during the a. Find the formula that Mr. Powers uses to determine the amount of money he will give his sons each week. b. William worked 15 hours in the yard and received $20. What was William's GPA from his last report card? 2xta for x5-2 5-93. Find values for a and b so that f(x) will f(x) = x2 -2 for - 23 255