50 points plz i just got 5 fillings im in

Can someone 50 first drop menu 0.80 or 0.75 or 1.20 or 4.00 second drop menu 4.00 or 0.75 or 0.25 or 3.75 3rd 15,6,10, or 9 4th yes or no

Can someone me out here number 4 plz

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).