  # Label Sides of a Triangle

In this worksheet, students will become familiar with labelling sides of a triangle to help solve trigonometry problems. Key stage:  KS 4

GCSE Subjects:   Maths

GCSE Boards:   AQA, Eduqas, Pearson Edexcel, OCR,

Curriculum topic:   Geometry and Measures, Mensuration

Curriculum subtopic:   Mensuration and Calculation Triangle Mensuration

Difficulty level:   #### Worksheet Overview   Questions

How can you find the height of this mountain?

How can this mountaineer draw an accurate map?

How did sailors navigate before GPS?

How can computers rotate images so that they can be viewed from many different directions?

They look at angles and sides of triangles and make connections between them.

This is pretty cool stuff really.

This is called Trigonometry.

Trigonometry is concerned with calculating the sides of triangles, angles within them.

There are three important ratios that you will need to know.  Sine, Cosine and Tangent.

These ratios are in terms of the sides of a right angled triangle and an angle.

Before you can solve anything using Sine, Cosine and Tangent accurately, you need to be able to label the triangles correctly.

Things to remember

The longest side of a right angled triangle is called the hypotenuse (H)

The side opposite the angle is called the opposite side (O)

The side right next to the angle is called the adjacent side (A) Look at the diagram above.

Label the hypotenuse first, as it is the easiest to spot.

Then go to the angle and pick up the opposite side.

That just leaves the adjacent side to label.

I always do it in that order, as it can be easy to get the opposite and adjacent muddled up.

Now let's look at labelling the adjacent. When you want to find the adjacent angle, find the angle in your diagram and draw a line along the side

Let's tri...

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