# Integral of sin(1-x)sinx

## Homework Statement

integral of sin(1-x)sinx dx

## The Attempt at a Solution

so i did by parts once and got -sinxcos(1-x) - integral of -cos(1-x)cosx dx

then i did by parts again and got -sinxcos(1-x) + cosxsin(1-x) - integral of -sin(1-x)sinx dx

if you take out the negative on the last integral you end up where you started? any one know where i messed up?

## Answers and Replies

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Instead of parts, you could try using a double angle formula on sin(1-x).

oh i think i see it i forgot to divide by the -1 each time i took the integral in the by parts

nevermind i still did not get the right answer how do i use double angle on sin(1-x_ i thought it had to be in the form sin2x?

fzero