Question

is the value of cos square 67 degree minus sin square 23 degree

Answer 1

Hey there!

We know that,
cos²B - sin²A = cos(A + B) * cos ( A - B)

Now,
cos²67° - sin²23°
= cos(67 + 23 ) * cos( 67 - 23 )
= cos ( 90 ) * cos45
= 0 * 1/√2 .
= 0

cos²67 -sin²23 = 0 .

Quick Alternative : [ cos²67-sin²23 = cos²(90-23) - sin²23 = sin²23 - sin²23 = 0 ]

[ cos²67-sin²23 = cos²67-sin²(90-67) = cos²67-cos²67 = 0 ]

Hope helped!

Answer 2

HI ,

Cos²67 - sin²23

= cos² 67 - sin² ( 90 - 67 )

[ ∵sin ( 90 - X ) = cos X ]

= Cos² 67 - cos² 67

= 0

I hope this helps you.

: )