6. An isosceles triangle has a height of 12 cm and a base of 10 cm. What is its perimeter?

A. 32 cm
B. 36 cm
C. 39 cm
D. 60 cm



Answer :

To determine the perimeter of an isosceles triangle with a given height and base, let's follow the step-by-step method.

1. Identify the given information:
- The height of the triangle [tex]\( h = 12 \)[/tex] cm
- The base of the triangle [tex]\( b = 10 \)[/tex] cm

2. Calculate half the base:
The base of the isosceles triangle is divided into two equal parts by the height. Each part is:
[tex]\[ \text{half_base} = \frac{b}{2} = \frac{10}{2} = 5 \text{ cm} \][/tex]

3. Calculate the length of the two equal sides:
Using the Pythagorean theorem for the right triangle formed by the height, half the base, and one of the equal sides:
[tex]\[ \text{equal_side} = \sqrt{h^2 + \text{half_base}^2} \][/tex]
Substituting the given values:
[tex]\[ \text{equal_side} = \sqrt{12^2 + 5^2} = \sqrt{144 + 25} = \sqrt{169} = 13 \text{ cm} \][/tex]

4. Calculate the perimeter of the isosceles triangle:
The perimeter [tex]\( P \)[/tex] is the sum of all three sides, i.e., the base and the two equal sides:
[tex]\[ P = b + 2 \times \text{equal_side} \][/tex]
Substituting the known values:
[tex]\[ P = 10 + 2 \times 13 = 10 + 26 = 36 \text{ cm} \][/tex]

Hence, the perimeter of the isosceles triangle is [tex]\( 36 \)[/tex] cm.

So, the correct answer is:
OB) 36 cm.