I know some people will say 1/2 base x length but when the triangle is slanted how do you know which of the three sides to take as the base and the length ?
(i am revising for A level maths so dont feel the need to be restricted to primary school terminology's)
How do you work out the area of a triangle?
2008-04-15 2:38 pm
回答 (9)
2008-04-15 2:56 pm
✔ 最佳答案
Out of 3 sides you can take any side as base. But the height is perpendicular drawn on that side from the vertex which is opposite to the side.e.g. If you take side BC as base then height is perpendicular drawn on BC from vertex A.
2008-04-15 10:26 pm
Find the perimeter.
let s = half the perimeter (semiperimeter)
let a,b anc c be the lengths of the three sides.
sqrt [(s)(s-a)(s-b)(s-c)] = area
let s = half the perimeter (semiperimeter)
let a,b anc c be the lengths of the three sides.
sqrt [(s)(s-a)(s-b)(s-c)] = area
2008-04-15 10:11 pm
a = 1/2 * b * h
To find the area of a triangle, multiply the base by the height, and then divide by 2. The division by 2 comes from the fact that a parallelogram can be divided into 2 triangles. For example, in the diagram to the left, the area of each triangle is equal to one-half the area of the parallelogram.
To find the area of a triangle, multiply the base by the height, and then divide by 2. The division by 2 comes from the fact that a parallelogram can be divided into 2 triangles. For example, in the diagram to the left, the area of each triangle is equal to one-half the area of the parallelogram.
參考: More info (area of a triangle):
http://www.mathgoodies.com/lessons/vol1/area_triangle.html
2008-04-15 9:56 pm
If a and b are two sides of the triangle and c is the included angle (i.e., the angle between a and b) then
area = (a)(b)sin(c)/2
area = (a)(b)sin(c)/2
2008-04-15 9:52 pm
You can use any side as the base. The height is measured perpendicular from the base to the one point not touching the base. Think of the "height" as the elevation above the ground (i.e. the "base").
參考: Here's a java based description that illustrates the concept (you can grab and drag the corners of the triangle with your mouse):
http://www.clarku.edu/~djoyce/trig/area.html
2008-04-16 4:41 am
you just multiply height times length.That is all.
參考: lessonplancentral.com
2008-04-15 9:45 pm
If you have one of the angles you can use (1/2)absinC
2008-04-15 9:44 pm
1/2 x base x height
for the base u choose any side, then for the height..u measure "right angle" with the base up 2 the highest point. NOT along a side.
for the base u choose any side, then for the height..u measure "right angle" with the base up 2 the highest point. NOT along a side.
2008-04-15 9:43 pm
Area of Triangle = 1/2 * base * Perpendicular Height
Read this, it explains it very well (its hard to describe in words without pictures)......
http://www.mathgoodies.com/lessons/vol1/area_triangle.html
Read this, it explains it very well (its hard to describe in words without pictures)......
http://www.mathgoodies.com/lessons/vol1/area_triangle.html
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