Question

what is the exact value of sin15 ? (using the subtraction formula)

Answer 1

help!

Answer 2

I don't know about the subtraction formula (never heard of it) but the half angle identity should work

Answer 3

\[\sin^215=\frac{1-\cos 30}{2}=\frac{1-\sqrt{3}/2}{2}=\frac{2-\sqrt{3}}{4}\]
\[\sin15=\frac{\sqrt{2-\sqrt{3}}}{2}\]

Answer 4

That's it right there^

Answer 5

I think the subtraction formula would mean that you would take two sin values that you know and use them to get sin 15

Sin 45 - Sin 30

I will get back with the formula

Answer 6

OK here is the formula
sin(A−B) = sin A cos B − cos A sin B

Answer 7

im required to use this formula sin(s-t)= sin(s)cos(t) - cos(s)sin(t)

Answer 8

Sin(45-30) = sin45*cos30 - cos45*sin30

Answer 9

Sin 45 = sqrt2/2 cos 45 = sqrt2/2
sin 30 = 1/2 cos 30 = sqrt3/2

Answer 10

The difference identity! Yup that works better!

Answer 11

sqrt2/2*sqrt3/2 - sqrt2/2*1/2

sqrt6/2 - sqrt2/2

(sqrt6 - sqrt2) /2

Answer 12

would it be over 4 after multiplying

Answer 13

OOPS - yes

Answer 14

thanks so much!

Answer 15

U R Welcome