Question

find the value of cos square 40 degree + sin square 30 degree
​

Answer 1

ANSWER

cos

2

48

o

−sin

2

12

o

=cos(48+12)cos(48−12)[cos

2

A−sin

2

B=cos(A+B)cos(A−B)]

=cos60×cos36=

2

1

×

4

5

+1

8

5

+1