Compare Perimeter vs Circumference: Triangle (5-6) vs Circle (Radius 6)

Question

Look at the triangle and circle below.

Which has the larger perimeter/circumference?

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Video Solution

Solution Steps

00:00 Determine which of the following shapes has the larger perimeter
00:04 The perimeter of the triangle equals the sum of its sides
00:11 Side AC equals the sum of its parts (AD+DC)
00:16 Apply the Pythagorean theorem to the triangle ADB
00:23 Substitute in the relevant values and proceed to calculate to determine AD
00:34 This is the length of AD
00:44 Now apply the Pythagorean theorem to the triangle DCB
00:51 Substitute in the relevant values and calculate to determine DC
00:57 This is the length of DC
01:02 Now substitute the side lengths that we found into the equation for calculating perimeter
01:11 This is the perimeter of the triangle
01:17 Apply the formula for calculating the circumference of a circle
01:20 Two x pi multiplied by the radius (R)
01:23 Substitute in our radius value and we should obtain the circumference
01:29 This is the circumference of the circle (larger than the triangle)
01:33 This is the solution

Step-by-Step Solution

To determine which has the larger measurement, the triangle's perimeter or the circle's circumference, we need to compute both values.

Step 1: Calculate the perimeter of the Triangle
We are given two sides of the triangle: 6 and 5. Since it's implied to be a right triangle, we apply the Pythagorean theorem to find the third side, the hypotenuse c c :

c=62+52=36+25=61 c = \sqrt{6^2 + 5^2} = \sqrt{36 + 25} = \sqrt{61}

The perimeter P P of the triangle is:

P=6+5+6111+7.81=18.81 P = 6 + 5 + \sqrt{61} \approx 11 + 7.81 = 18.81

Step 2: Calculate the circumference of the Circle
The circumference C C of a circle with radius r r is given by the formula:

C=2πr C = 2 \pi r

Assuming the radius of the circle is equivalent to the '6' mentioned for the green line in the SVG:

C=2π×637.7 C = 2 \pi \times 6 \approx 37.7

Step 3: Compare the Triangle's Perimeter and the Circle's Circumference
We compare the values:

  • Perimeter of the Triangle: P18.81 P \approx 18.81
  • Circumference of the Circle: C37.7 C \approx 37.7

The circumference of the circle (37.7) is greater than the perimeter of the triangle (18.81).

Therefore, the circle has the larger measurement.

Conclusion: The circle has the larger perimeter.

Answer

The circle