Apparently in the drawing, the triangle which two sides are equal is isosceles. It is possible to find the area of an isosceles triangle, knowing length of its basis and height or on length of its basis and any side of a triangle.
It is required to you
- - geometrical formula for finding of the area of an isosceles triangle of AVS:
- S = 1/2 x b x h, where:
- - S - area of a triangle of AVS,
- - b - length of its basis EXPERT,
- - h - length of its height.
Instruction
1. Measure basis length the EXPERT of an isosceles triangle of ABC, usually length of the basis of a triangle is given in statements of the problem. Let length of the basis will be equal to 6 cm. Measure height of an isosceles triangle. Height is the piece which is carried out from top of a triangle is perpendicular to its basis. Let under the terms of a task h height = 10 cm.
2. Calculate the area of an isosceles triangle on a formula. For this purpose divide basis length the EXPERT in half: 6/2=3 cm. So, 1/2b=3 see. Increase a half of length of the basis the EXPERT of a triangle by h height length: 3 x 10=30 cm. Thus, you found the area of an isosceles triangle of AVS on length of its basis and height. If under the terms of a task length of height is unknown, but length of the party of a triangle is given, then at first find length of height of an isosceles triangle on formula h = 1/2 · √ (4a2 – b2).
3. Calculate length of height of an isosceles triangle on length of its parties and the bases. Let and - length of any party of an isosceles triangle, under the terms of a task it is equal to 10 cm. Having substituted values of lengths of the parties and the basis of an isosceles triangle in a formula, find length of its height of h=1/2x √ (4х100 – 36) =10 cm. Having calculated height of an isosceles triangle, continue calculations, having substituted the found values in the specified formula of finding of the area of a triangle on its height and the basis.