Answer:
4.number 1
5.number 2
Explanation:
4.Because the the expression tan can be written as sin divided by cos it will be beneficial to write the square of cos as cos multiplied by cos so that after canceling out we are left with cos multiplied by sin of the left hand side.
5.because transforming cos squared to 1-sin squared will allow us to to have a fraction where both the numerator and denominator are the same which equals one.