Question Details

An equilateral triangle has a height measuring 123 cm. Determine the area and perimeter of the triangle.

Options

A

Area = 1083 cm2, Perimeter = 60 cm

B

Area = 483 cm2, Perimeter = 36 cm

C

Area = 723 cm2, Perimeter = 48 cm

D

Area = 1443 cm2, Perimeter = 72 cm

Show Answer

Correct Answer :

Option D

Area = 1443 cm2, Perimeter = 72 cm

Solution :

The correct option is Area = 1443 cm2, Perimeter = 72 cm.

To find the area and perimeter of an equilateral triangle, we first need to determine its side length, denoted as a.

In an equilateral triangle, all three sides are equal, and the height (h) divides the triangle into two congruent right-angled triangles.

The relationship between the height h and side length a of an equilateral triangle is given by the formula:

h=32a

We are given that the height is 123 cm. Substituting this value into the height formula:

123=32a

To solve for a, divide both sides of the equation by 3:

12=12a

Multiply both sides by 2:

a=24 cm

Now that we have found the side length a=24 cm, we can calculate both the perimeter and the area of the triangle.

Step 1: Calculate the Perimeter
The perimeter of an equilateral triangle is the sum of its three equal sides:

Perimeter=3×a

Perimeter=3×24=72 cm

Step 2: Calculate the Area
The formula for the area (A) of an equilateral triangle is:

A=34a2

Substitute a=24 cm into the area formula:

A=34×242

A=34×576

A=1443 cm2

Therefore, the area of the triangle is 1443 cm2 and the perimeter is 72 cm.

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