How can i proof this equation with a trigonometric identity-half angle? (starting with the left side)

Geometry: determine whether segment mn is parallel to segment kl. justify your answer. jm 6 mk 3 jn 8 nl 4

Which of the following represents a number squared is equal to twenty more than nine times that number ? a) x squared = 9x + 20 b) x squared = 20x + 9 c) x squared > 9 + 20x d) x squared = 9 + x + 20

Can someone check if i did this correct. it’s number 4 if you’re wondering.