Question

Integrals,

Can you please tell me how do I go about solving this ? http://screencast.com/t/B32IKbUH9

Answer 1

you know cos 2theta formula ?

Answer 2

no :/

Answer 3

convert sin^2 @ to cos 2@ by 1-cos 2@ = 2sin^2 @

Answer 4

whats @ ??

Answer 5

@ is theta(angle)

Answer 6

hm

Answer 7

*confused* hold on

Answer 8

@hartnn which formula where u talking about earlier ??

Answer 9

there are 4 formulas for cos2x
all 4 are very important.
3 of them i will write now

Answer 10

\(\Large \cos2x = \cos^2x-\sin^2x = 2\cos^2x-1 = 1-2\sin^2x\)
these.

Answer 11

heard of them ?

Answer 12

aah no, first time :D

Answer 13

I will use them

Answer 14

you need trigonometry before calculus

Answer 15

:D

Answer 16

1/2 int of (1 - 2sin^2(x) what then ??

Answer 17

you had sin^2 5theta

so you will need to isolate sin^2 x from
cos 2x = 1-2sin^2x
can u ?

Answer 18

hm

Answer 19

int of dx - 2 int of sin ^2 x dx

Answer 20

forget all of this, wait

Answer 21

firget about the integral lol
just isolate sin^2 x from
cos 2x = 1-2sin^2x

Answer 22

*forget

Answer 23

x/2 - sin(10theta)/2 + c

Answer 24

theta/2 - sin(10theta)/20 + c

Answer 25

^

Answer 26

has to be it

Answer 27

yes, correct :)