Question

please solve this question iwill give brainliest​

Answer 1

Answer:

1/3

Step-by-step explanation:

cos⁴ x - sin⁴ x = a

( cos²x )² - ( sin² x )² = a

use Identity : a² - b² = ( a + b ) ( a- b )

( cos² x - sin² x ) ( cos² x + sin² x ) = a

use Identity : cos² x + sin² x = 1

( cos² x - sin² x ) × 1 = a

cos² x - sin² x = a

cos 2x = a

now given that....

x = 60°

hence. .

cos 2(60°) = a

cos 120° = a

1/2 = a

now....

( 1 - a ) / ( 1 + a )

= ( 1 - ½ ) / ( 1 + ½ )

= ½ / 3/2

= 1/3