In these lessons, we will learn how to find the area of a triangle using the sine function when given side-angle-side (SAS).
The most common formula for the area of a triangle would be:
Another formula that can be used to obtain the area of a triangle uses the sine function. It allows us to find the area of a triangle when we know the lengths of two sides and the size of angle between them.
The formula is
Area of triangle = ab sin C
Remember that the given angle must be between the two given sides.
Find the area of triangle PQR if p = 6.5 cm, r = 4.3 cm and ∠ Q = 39˚. Give your answer correct to 2 decimal places.
Area of triangle PQR
= pr sin Q
= sin 39˚
= 8.79 cm2
In triangle ABC if AC = 2BC and ∠ C = 112˚. The area of triangle ABC is 16.3 cm Find the length of BC . Give your answer correct to 2 significant figures.
Let the length of BC = x
and the length of AC = 2x
x = 4.19 cm
So, BC = 4.2 cm
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