Question

Find the length of the smallest side of a right angled triangle with other two sides 15 cm and 12 cm.

• A. 8cm
• B. 9cm
• C. 10cm
• D. 11cm

Answer 1

Answer:

B. 9cm

The correct answer is Option B (9 cm).

To find the smallest side, we use the Pythagorean Theorem ($a^2 + b^2 = c^2$). In a right-angled triangle, the longest side is always the hypotenuse ($c$). Since the question asks for the smallest side, we assume the longest given side (15 cm) is the hypotenuse.

Step-by-Step Calculation

1. Set up the equation:
   Let the missing side be $x$.
   $x^2 + 12^2 = 15^2$

2. Square the known numbers:
   $x^2 + 144 = 225$

3. Isolate $x^2$:
   $x^2 = 225 - 144$

4. $x^2 = 81$

5. Find the square root:
   $x = \sqrt{81} = \mathbf{9 \text{ cm}}$