Year 9 Interactive Maths - Second Edition

Finding Side-Lengths

We can use the trigonometric ratios sine, cosine and tangent to find any side-length of a right-angled triangle if we know another angle and one side-length.

Using the Sine Ratio

Example 3

Find the value of the pronumeral, correct to 2 decimal places, in the given diagram.

Solution:

Example 4

Find the length of the hypotenuse, correct to 2 decimal places, in the given diagram.

Solution:

Let the length of the hypotenuse be x cm.

So, the length of the hypotenuse is 51.91 cm.