How old do i have to be to drop out of high school?

What basic trigonometric identity would you use to verify that sin x cos x tan x =1-cos^(2)x?

This is so harddd! solve. 1 + 1 = solve 4 + 4 = solve 3 x 3

Students are given 3 minutes for each multiple-choice question and 5 minutes for each free-response question on a test. there are 15 questions on the test, and students are given 51 minutes to take it.how many multiple-choice questions are on the test?