Steply

Simplify sin x sec x

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

Step by step

The question

Question: simplify sin x × sec x.

Simplify means: write it as simply as we can.

sin x × sec x

1 Write in sin and cos

Everything is easier in sin and cos.

sec is 1 over cos.

sec x = 1cos x

We put them in.

Tops go on top, bottoms at the bottom.

= sin xcos x

2 Name it

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

= tan x

So it simplifies to tan x.

3 Check

Let's check with a number: x = 30°.

On the calculator, sin 30° × sec 30° is about 0.5774.

x = 30°: sin 30° × sec 30° ≈ 0.5774

And tan 30° is about 0.5774.

The same!

So it is right.

tan 30° ≈ 0.5774

Let's look back.

First: write in sin and cos.

Then: name it.

Last: check.

Answer
= tan x

Your turn

Try this one yourself, then check:

cos x × csc x
Show the answer
cot x

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