Steply

Simplify sin x cos x / sin^2 x

Step by step, with the reason for every step · Trig identities · Trigonometry

Step by step

The question

Question: simplify sin x × cos x over sin² x.

Simplify means: write it as simply as we can.

sin x × cos xsin2 x

1 Cancel

A square means times itself: sin² x = sin x × sin x.

We write every one out.

= sin x × cos xsin x × sin x

Careful!

sin x means the sine of x.

It is one thing.

We cross out a whole sin x, never the x alone.

Careful: sin x is one thing

Every sin x on top has a partner at the bottom.

Each pair over itself is 1.

Cross them out.

What is left: cos x over sin x.

= cos xsin x

2 Name it

cos x over sin x has its own name: cot x.

= cot x

So it simplifies to cot x.

3 Check

Let's check with a number: x = 30°.

On the calculator, sin 30° × cos 30° over sin² 30° is about 1.7321.

x = 30°: sin 30° × cos 30°sin2 30° ≈ 1.7321

And cot 30° is about 1.7321.

The same!

So it is right.

cot 30° ≈ 1.7321

Let's look back.

First: cancel.

Then: name it.

Last: check.

Answer
= cot x

Your turn

Try this one yourself, then check:

sin x × cos xcos2 x
Show the answer
tan x

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