Thread: area of triangle

The dimensions of a triangle are 13, 13, and 24. What is the area in square units of this triangle?

A) 30 B) 60 C) 90 D) 156 E) 312

Hello, sri340!

Obviously, you didn't make a sketch . . .

The dimensions of a triangle are 13, 13, and 24.
What is the area of this triangle?

. . A) 30 . . B) 60 . . C) 90 . . D) 156 . . E) 312

Code:

                      *
            13    *   |   *    13
              *       |h      *
          *           |           *
      * - - - - - - - * - - - - - - - *
              12             12

The base of this triangle is 24.

Can you find the height ?

Originally Posted by sri340

The dimensions of a triangle are 13, 13, and 24. What is the area in square units of this triangle?

A) 30 B) 60 C) 90 D) 156 E) 312

In a test situation, a sketch as Soroban suggested would have helped immensely, & you probably could have solved it immediately.

Alternatively, use could use Heron's formula

Area =

s = = 25

Area =

Area =

.You should not require a calculator to extract that square root.

That's because each half of Soroban's picture is a "5-12-13" right triangle!

Originally Posted by sri340

The dimensions of a triangle are 13, 13, and 24. What is the area in square units of this triangle?

A) 30 B) 60 C) 90 D) 156 E) 312

the triangle is isosceles with base = 24 units
dividing it into two congruent right angled triangles, each has hypotenuse = 13 and the base = 24/2 = 12
the other side (height) = = 5
so the area is 24 x 5 / 2 = 60 sq units