The area of a triangle is cm² and its sides are in the ratio 4 : 5 : 7. What is its perimeter?
Options
A
21 cm
B
24 cm
C
27 cm
D
32 cm
Answer & Analysis
Answer
D
Analysis
Question Analysis
Given the area of a triangle and the ratio of its sides, the key is to represent the sides using a common variable, calculate the semi-perimeter, and then apply Heron's formula to find the variable and ultimately the perimeter.
Key Concept Explanation
Heron's Formula: For a triangle with side lengths , , , the area , where is the semi-perimeter.
Ratio Representation: When sides are in a ratio like , we can represent them as , , and to simplify calculations.
Step-by-Step Solution
1. Represent the sides and calculate the semi-perimeter:
Let the sides be , , .
The perimeter , so the semi-perimeter .
2. Apply Heron's formula:
Substitute into Heron's formula:
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