How to solve it because i have no idea

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

Find the perimeter of the figure shown above. a. 40 cm c. 52 cm b. 60 cm d. 75 cm select the best answer from the choices provided

He mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 x 10^23. which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?