# Help With Trig Inequality

## Homework Statement

I am attempting to show that $-x \leq sin(x) \leq x$ for x>0 and thus $\int^1_0 nxsin(\frac{1}{nx})dx$ converges to 1.

## Homework Equations

I know that I need to use the fact that I have shown that the limit as T tends to infinity of $\int^T_1 \frac{cos(x)}{\sqrt{x}}dx$ exists.

## Answers and Replies

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LCKurtz
Homework Helper
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## Homework Statement

I am attempting to show that $-x \leq sin(x) \leq x$ for x>0 and ...
The -x part is trivial and for the rest integrate both sides of cos(t) ≤ 1 between 0 and x, x > 0.

The -x part is trivial and for the rest integrate both sides of cos(t) ≤ 1 between 0 and x, x > 0.
OK I've done this and I get the inequality I need. But can I just check, I don't understand how I have used the equation I need to in the OP?

For the second part if I know that -x<= sinx <= x then -1<=nx(sin(1/nx)) <= 1 but then I'm a bit stuck