Multiplying a number by 4 then dividing by 5 is the same as multiplying by what number?

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

Svetlana's hair is 4 4 centimeters ( cm cm) long. her hair grows 1 . 5 cm 1.5cm per month. svetlana wants her hair to be less than 1 6 cm 16cm long. write an inequality to determine the number of months, m m, svetlana can allow her hair to grow so that it is less than 1 6 cm 16cm long.

How do i do this activity, is appreciated