Question

Select the correct answer.

A triangle has vertices (-1, 2), (3, 1), and (7, 2). What is the approximate perimeter of the triangle? Round your answer to the nearest hundredth.
A.
16 units
B.
16.24 units
C.
16.31 units
D.
17 units

Answer 1

B. 16.24 units

Explanation:

Answer 2

B. 16.24 units

Explanation:

The actual perimeter is 8 + 2√17 ≈ 16.2462 ≈ 16.25.

The closest answer choice is the one shown above.

_____

The distance formula tells you the length of the short sides is ...

d = √(4² +1²) = √17

Both short sides are the same length, and the long side is length 8, so the perimeter is ...

P = 8 + 2√17 ≈ 16.2462 . . . . . rounds to 16.25

_____

Comment on the offered answer choice

We often see cases of incorrect rounding in the answers to problems. This is another example.

If each line segment length is rounded to hundredths before they are added up to find the perimeter, the (incorrect) result will be 16.24. Anytime rounding is required, the only place in the calculation where it should be done is for the final answer.