cos a cos b - sin a sin b = cos(a+b)
= cos 70
cos45cos25 - sin 45sin25 = ??
a. cos70
b. sin70
c. cos 20
d. sin 20
which answer is correct ?
1 answer
a. cos70
b. sin70
c. cos 20
d. sin 20
which answer is correct ?
1 answer