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Area of a Triangle
Area of a Triangle
How do I find the area of a non-right triangle?
The area of
any triangle
can be found using the formula
Where
C
is the angle between sides
a
and
b
You need to remember it
Be careful to label your triangle correctly so that
C
is always the angle
between
the two sides
Sin 90° = 1 so if C = 90° this becomes Area = ½ × base × height
If you know the area you can use the formula to find the length of a side or the angle
Using inverse sin will always give you an acute angle
Subtract the value from 180 if you need the obtuse angle
Exam Tip
Remember to check that your calculator is in degrees mode!
Worked example
The following diagram shows triangle
.
,
,
.
Calculate the area of triangle .
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