HELPPP plz due soon

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

According to the 2008 u.s. census, california had a population of approximately 4 × 10^7 people and florida had a population of approximately 2 × 10^7 people. which of the following is true? a. the population of florida was approximately two times the population of california. b. the population of florida was approximately twenty times the population of california. c. the population of california was approximately twenty times the population of florida. d. the population of california was approximately two times the population of florida.

An arc subtends a central angle measuring 7pi/4 radians what fraction of the circumference is this arc?