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Name |
Area of Triangle |
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Equation |
A
=
1
2
x
h
=
1
2
a
b
sin
C
A
=
s
(
s
−
a
)
(
s
&-ThinSpace;
−
b
)
(
s
-
c
)
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Definition of terms |
A = area, x = base of triangle, h = height of triangle measured on a line perpendicular to the base, a b c = sides of triangle, A B C = interior angles of triangle directly opposite to the side of the same letter,
s
=
1
2
(
a
+
b
+
c
)
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Comments |
The area of a triangle is commonly quoted as "half base times height", which is the first formula here. The second formula states that the area of a triangle is equal to the product of the lengths of two sides and the sine of the angle between them.
The third formula above, also known as Heron's formula, gives an expression for the area entirely in terms of the lengths of the three sides. |
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References
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CRC Standard Mathematical Tables , 26th edition, CRC, 1981 |
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