Idont understand this. i wasn't at school when we got the notes. i really need

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

Answer for 10 points show work you guys in advanced < 3

Helll ! 1,400 tons of wheat of two different varieties was delivered to the silo. when processing one variety, there was 2% of waste and 3% during the processing of the second variety of wheat. after the processing, the amount of remaining wheat was 1,364 tons. how many tons of each variety of wheat was delivered to the silo?