The three trigonometric ratios; sine, cosine and tangent are used to calculate angles and lengths in right-angled triangles. The sine and cosine rules calculate lengths and angles in any triangle.

Part of

The area of any triangle can be calculated using the formula:

To calculate the area of any triangle the lengths of two sides and the angle in between are required.

Calculate the area of the triangle. Give the answer to 3 significant figures.

Use the formula:

area = 12.4 cm^{2}

It may be necessary to rearrange the formula if the area of the triangle is given and a length or an angle is to be calculated.

- Question
The area of the triangle is 5.45 cm

^{2}. Calculate the size of the angle YXZ. Give the answer to the nearest degree.Use the formula:

Rearrange the equation to make the subject.

Divide both sides by 8.48.

. Do not round this answer yet.

To calculate the angle use the inverse sin button on the calculator ( ).

C = 40°

The angle YXZ is 40°.