Question

(1-sin(pi/8))(1+sin(pi/8))

Answer 1

1-sin^2(pi/8)

Answer 2

1+sin(pi/8)-sin(pi/8)-sin^2(pi/8)

Answer 3

=cos^2(pi/8)

Answer 4

And that is equal? How to find out :) ?

Answer 5

\[\cos^2x+\sin^2x = 1\]\[1-\sin^2x = \cos^2x\]

Answer 6

You want to evaluate \(\cos^2(\pi/8)\)?

Answer 7

yes :)

Answer 8

How to find out what cos2(π/8) is

Answer 9

cos^2(pi/8)

Answer 10

Okay, that's easy enough. Use the identity
\[\cos^2 u = \frac{1+\cos 2u}{2}\]

Answer 11

\(u = \pi/8\) so \(2u = \pi/4\) and you can find the \(\cos\) of that easily.

Answer 12

cos^2x=(1+sqr2/2)/2

Answer 13

?

Answer 14

=(2+sqr2)/4

Answer 15

That's correct. About 0.853553 if evaluated.

Answer 16

Tyvm :)

Answer 17

yw :)

Answer 18

study those identity lists!

Answer 19

Will do :D