Chem Tech makes paper cones

used to filter liquids in lab
experiments. To make the paper
cones, the company starts with the
net of the shape, where the slant
height is needed. The company
wants the height of the cones to be 6
cm. If they make the diameter 13
cm, what must the slant height be?
Use the Pythagorean Theorem and
round the answer to the nearest
tenth.

1 answer

To find the slant height of the cone, we can use the Pythagorean Theorem. A cone consists of a height, a radius (half of the diameter), and a slant height which acts as the hypotenuse of a right triangle formed by these elements.

  1. Find the radius: The diameter of the cone is given as 13 cm. Therefore, the radius (r) is: \[ r = \frac{diameter}{2} = \frac{13 \text{ cm}}{2} = 6.5 \text{ cm} \]

  2. Identify the height: The height (h) of the cone is given as 6 cm.

  3. Use the Pythagorean Theorem: The relationship between the radius, height, and slant height (l) can be expressed as: \[ l^2 = r^2 + h^2 \]

    Substituting the known values: \[ l^2 = (6.5 \text{ cm})^2 + (6 \text{ cm})^2 \] \[ l^2 = 42.25 \text{ cm}^2 + 36 \text{ cm}^2 \] \[ l^2 = 78.25 \text{ cm}^2 \]

  4. Calculate the slant height: Now take the square root of both sides: \[ l = \sqrt{78.25 \text{ cm}^2} \approx 8.84 \text{ cm} \]

  5. Round to the nearest tenth: Rounding 8.84 to the nearest tenth gives: \[ l \approx 8.8 \text{ cm} \]

Thus, the required slant height is approximately 8.8 cm.