Question

What is the value of cos2

31° – sin2

59°.​

Answer 1

Step-by-step explanation:

$= { \cos}^{2} 31 - { \sin }^{2} 59 \\ = { \cos }^{2}31 - (1 - { \cos}^{2} 31) \: \: (or) = (1 - { \sin }^{2} 59) - { \sin }^{2} 59\\ = { \cos }^{2} 31 - 1 + { \cos }^{2} 31 \: \: (or) =1 - { \sin }^{2} 59 - { \sin }^{2} 59 \\ = 2 { \cos }^{2} 31 - 1 \: \: (or) = 1 - 2 { \sin }^{2} 59$