If the sides of an equilateral triangle are shortened by 3 units, 4 units and 5 units respectively and a right triangle is formed then the side of an equilateral triangle is:
Correct Answer
✅ Option c — 8 units
All Options:
- A6 units
- B7 units
- C8 units
- D10 units
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Detailed Solution & Explanation
When the sides are shortened by units, units, and units respectively, the new side lengths are:
Since these new side lengths form a right-angled triangle, they must satisfy the Pythagorean theorem. The longest side (hypotenuse) will be the one with the smallest subtracted value, which is . The other two sides are the legs.
Applying the Pythagorean theorem:
Expanding both sides:
Rearranging all terms to the right-hand side to form a quadratic equation:
Factoring the quadratic equation:
This gives two possible values for :
Let's evaluate both values:
- If , the side lengths are , , and . Since side lengths cannot be zero or negative, is discarded.
- If , the side lengths are , , and . A triangle with sides , , and is a valid right-angled triangle because .
Thus, the side of the original equilateral triangle is units, which corresponds to Option C. (Note: The raw JSON specifies Option B, which is units, but that is mathematically incorrect; Option C is the unique, correct solution).
Hence, **Option C** is the correct answer.
About This Chapter: Equations
Paper
Paper 3: Quantitative Aptitude
Weightage
4-6 Marks
Key Topics
Linear, Quadratic and Cubic Equations
This chapter covers Linear, Quadratic and Cubic Equations and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.
View Official ICAI SyllabusExam Strategy Tip
This topic carries 4-6 Marks weightage. Focus on understanding core concepts rather than memorizing.
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