Question

Trigonometry: Calculate sin 75degrees. Use the fact that: cos (u + v) = cosucosv - sin u sinv

Answer 1

cos 75=cos(45+30)=cos45cos30-sin45sin30
=1/root(2)*root(3)/2-1/root(2) *1/2
=root(3)-1/root(2)

Answer 2

do you mean cos 75?

Answer 3

sai1234 has it

Answer 4

Sin 75  could be written as sin ( 30+45)
Sin(A+B) = sinA cosB + cos A sinB
SinB (30 + 45) = sin 30 cos 45 + cos 30 sin 45{ sin 30 = 1/2, cos 30 = sqrt( 3)/2, sin45= cos 45=1/sqrt (2)}
Putting the values
1/2x 1/ sqrt (2) + sqrt(3)/2 x 1/ sqrt(2)
1/2sqrt(2) + sqrt(3) / 2sqrt(2).   Taking LCM
[1+ sqrt(3)]/2sqrt(2)

Answer 5

sin(750=root(1-cos752)
root(1-(root(3)-1/root(2))^2)
=0.96

Answer 6

thanks @sai1234 !!

Answer 7

and @nishika17

Answer 8

Welcome