Question

tell me the answer please ​

Answer 1

To find: Cos^2 67 -  Sin^2 23

Formula: Cos^2A - Sin^2B = Cos ( A + B ) * Cos ( A - B )

Here, A = 67, B = 23  

Substituting them, We get: Cos (67 + 23 ) * Cos( 67 - 23 )

Cos ( 90 ) * cos ( 45  )

Substituting values, 0 * 1/√2 .

Hence, Cos^2 67 -  Sin^2 23 = 0

Answer 2

Answer:

change sign into cos check NCERT book