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Contents
Area of Sector & Length of Arc
Area of Triangle
Surface Area of Cones & Pyramids
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Area of
Triangle You can see from the figure below that a triangle can be rearranged to form a rectangle. The area of a triangle is found from the formula ½ x base x height.
Consider
the figure on the right. Area of ABC = ½ x b x h --------(1) In BCD, sin C = h/a h = a sin C --------(2) Sub (2) into (1): ½ab sin C Consider
the figure on the right, where angle C is an obtuse angle. Area of ABC = ½ x b x h --------(1) In BCD, sin C = h/a h = a sin C --------(2) Sub (2) into (1): ½ab sin C By considering sin A and sin B in a similar way, we can prove that ½bc Sin A = ½ac sin B Therefore we have the following:
Area
of ABC = ½ab sin C = ½bc Sin A = ½ac sin
B
Example 1
base = 24cm2
x 2 / 8 cm
= 6 cm
For
example on the sin rule (½ ab sin C), please visit our page on Solution
of Triangles (Sine)
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Given that the
area of a triangle is 24cm2 and its height is 8cm, find its base.
Area of triangle
= ½ base x height
