GCSE Maths: Understanding Trigonometry with questions

Trigonometry: GCSE Maths
Understanding Trigonometry
Trigonometry is a branch of mathematics that deals with the relationships between the sides
and angles of triangles. It is particularly useful in solving problems involving right-angled
triangles.
The Trigonometric Ratios
There are three main trigonometric ratios:
 Sine (sin): Opposite side / Hypotenuse
 Cosine (cos): Adjacent side / Hypotenuse
 Tangent (tan): Opposite side / Adjacent side
These ratios are defined for right-angled triangles, where:
 The hypotenuse is the side opposite the right angle.
 The opposite side is the side opposite the angle of interest.
 The adjacent side is the side next to the angle of interest.




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rightangled triangle with labels for hypotenuse, opposite, and adjacent sides
Using Trigonometric Ratios to Find Sides and Angles
You can use the trigonometric ratios to find the length of a side or the measure of an angle
in a right-angled triangle.
Example 1: Finding a side If you know the measure of an angle and the length of one side,
you can use the appropriate trigonometric ratio to find the length of another side.