8

Set 5: Triangles

Explanation

Answer: C

A triangular picture frame has sides measuring 10 centimeters and 5 centimeters. If the total perimeter is 21 centimeters, find the length of the third side.

A.

3

B.

16

C.

6

✓ Correct
D.

12

Detailed Explanation

Choice C is correct. The perimeter of a triangle is the sum of all three sides. 1. Total perimeter: 21 centimeters Two known sides: 10 + 5 = 15 centimeters Third side: 21 - 15 = 6 centimeters Therefore, the third side is 6 centimeters.

Key Steps:

The correct answer is 6

Why others are wrong:
A: This would give an incorrect result. Choice A is incorrect and may result from a calculation error.
B: This would give an incorrect result. Choice B is incorrect and may result from a calculation error.
D: This would give an incorrect result. Choice D is incorrect and may result from a calculation error.

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