Question

WILL GIVE BRAINIEST! Triangle ABC is isosceles with AB = BC. If AC = 20 and {ABC} = 240, then find the perimeter of triangle ABC.

Answer 1

Answer:

72

Step-by-step explanation:

Since the triangle's area is 240, the base * height must equal 480 because for the area of a triangle it is half of that. Since you know that the base AC = 20, find out what you can multiply by 20 to get 480. This gives you a result of 24. Now that the height is found divide the triangle into two right triangles. Now Just use the pythagorean theorem to find the legs of the triangles. AB = BC = 26. 26 + 26 + 20 = 72 which is the perimeter.  

Answer 2

The Perimeter of triangle ABC is 72 unit

What is isosceles triangle ?

Isosceles triangles are those triangles that have at least two sides of equal measure. We know that triangles are three-sided enclosed polygons and they are classified as equilateral, isosceles, and scalene, based on the length of their sides. In this article, we will learn about the definition of an isosceles triangle and its properties.

We have

AC = 20 unit

Area of triangle {ABC} = 240 unit square

AB = BC

draw the altitude to AC, let’s call it BD (Construction)

Now,

we know the area of triangle = 1/2 × AC × BD

240 = 1/2 × 20 × BD

BD = 240 × 2/20

BD = 24 unit

AD=CD (Altitude to base of isosceles triangle)

2AD=AC

2AD=20

AD=10 (Parts-Whole Postulate, substitution)

in ∠ABC using Pythagorean theorem

$AD^{2}$ + $BD^{2}$ = $AB^{2}$

$AB^{2}$ = $10^{2}$ + $24^{2}$

AB = $\sqrt{100 + 576}$

AB = $\sqrt{676}$

AB=26

AB=BC=26 (Definition of Isosceles Triangle)

AC = 20

Perimeter of triangle ABC = AB+BC+AC (definition of Perimeter)

Perimeter of triangle ABC = 26 + 26 +20

Perimeter of triangle ABC = 72 unit

To learn more about isosceles triangle from here

https://brainly.in/question/26765711

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