Question

Two shapes are shown below, one isosceles triangle and one rectangle. The dimensions can be represented by algebraic expressions, as shown in the diagram below. They both have the same area. Find the numerical value of the perimeter of the isosceles triangle. show full calculations please

Answer 1

Answer:

Perimeter of Isosceles Triangle = 16 units

Step-by-step explanation:

Area of rectangle is given by the formula;

Area = 1/2 × base × height

From the diagram, base = 6x - 6 and height = 6x - 8

Thus,Area = 1/2 × (6x - 6) × (6x - 8)

Area = (3x - 3)(6x - 8) = 18x² - 42x + 24

Secondly, area of rectangle is given by;

Area = length x breadth

So, area of rectangle in question = (6x - 9)(3x - 2) = 18x² - 39x + 18

We are told both the area of the triangle and the rectangle are the same, so let's equate both areas;

18x² - 42x + 24 = 18x² - 39x + 18

18x² will cancel out and rearranging, we have;

24 - 18 = 42x - 39x

6 = 3x

x = 6/3

x = 2

Plugging 2 for x for the height and base of the triangle, we have;

base = 6(2) - 6 and height = 6(2) - 8

Base = 6 and height = 4

So,let's find the slant height of the isosceles triangle.

Dividing the base by 2,we have; 6/2 = 3

So,using Pythagoras theorem, let the slant height be h, so we have;

h² = 3² + 4²

h² = 9 + 16

h² = 25

h = √25

h = 5

2 slant sides of isosceles triangle are the same. So perimeter = 5 + 5 + 6 = 16 units