## Volume of Pyramids and Cones Worksheet Answers

### Introduction

Understanding the concepts of volume in geometry is essential for students to excel in mathematics. One of the key topics in volume calculations is finding the volume of pyramids and cones. To help students practice and reinforce their understanding of this concept, teachers often provide worksheets with various exercises. In this article, we will provide detailed answers to a volume of pyramids and cones worksheet, allowing students to check their work and gain confidence in their calculations.

### Worksheet Question 1: Finding the Volume of a Pyramid

Question: Calculate the volume of a pyramid with a base area of 36 square units and a height of 8 units.

Answer: To find the volume of a pyramid, we can use the formula V = (1/3) * base area * height. Plugging in the given values, we get V = (1/3) * 36 * 8 = 96 cubic units.

### Worksheet Question 2: Finding the Volume of a Cone

Question: Determine the volume of a cone with a radius of 5 units and a height of 10 units.

Answer: The formula for finding the volume of a cone is V = (1/3) * π * radius^2 * height. Substituting the given values, we have V = (1/3) * π * 5^2 * 10 = (1/3) * π * 25 * 10 = 250π cubic units.

### Worksheet Question 3: Comparing the Volumes of a Pyramid and a Cone

Question: A pyramid and a cone have the same base area and height. Compare their volumes.

Answer: Since the pyramid and the cone have the same base area and height, their volumes will be in the ratio of 1:3. This means that the volume of the cone will be three times greater than the volume of the pyramid.

### Worksheet Question 4: Applying the Volume Formula to Real-Life Problems

Question: A juice glass is in the shape of a cone with a radius of 3 cm and a height of 10 cm. Calculate the volume of juice the glass can hold.

Answer: Using the volume formula for a cone, we can calculate the volume as V = (1/3) * π * 3^2 * 10 = (1/3) * π * 9 * 10 = 30π cubic cm. Therefore, the juice glass can hold 30π cubic cm of juice.

### Worksheet Question 5: Solving for the Height of a Cone

Question: A cone has a volume of 100 cubic units and a radius of 4 units. Find the height of the cone.

Answer: Rearranging the volume formula for a cone, we can solve for the height: height = (3 * volume) / (π * radius^2). Substituting the given values, we have height = (3 * 100) / (π * 4^2) = 300 / (16π) = 18.87 units (rounded to two decimal places).

### Worksheet Question 6: Volume of a Frustum of a Cone

Question: Calculate the volume of a frustum of a cone with radii of 4 units and 2 units and a height of 6 units.

Answer: The formula for the volume of a frustum of a cone is V = (1/3) * π * (R^2 + r^2 + Rr) * height, where R is the larger radius, r is the smaller radius, and height is the height of the frustum. Plugging in the given values, we get V = (1/3) * π * (4^2 + 2^2 + 4*2) * 6 = (1/3) * π * (16 + 4 + 8) * 6 = 96π cubic units.

### Worksheet Question 7: Calculating the Volume of a Pyramid with an Irregular Base

Question: A pyramid has a triangular base with side lengths of 5 units, 6 units, and 7 units. Its height is 8 units. Determine the volume of the pyramid.

Answer: To find the volume of a pyramid with an irregular base, we first need to calculate the base area. Using Heron's formula, we find the semi-perimeter of the triangle: s = (5 + 6 + 7) / 2 = 9 units. The base area can be calculated using the formula A = √(s * (s - a) * (s - b) * (s - c)), where a, b, and c are the side lengths of the triangle. Plugging in the values, we get A = √(9 * (9 - 5) * (9 - 6) * (9 - 7)) = √(9 * 4 * 3 * 2) = √(216) ≈ 14.7 square units. Finally, we can calculate the volume using the formula V = (1/3) * base area * height: V = (1/3) * 14.7 * 8 ≈ 39.2 cubic units.

### Worksheet Question 8: Solving for the Height of a Pyramid

Question: A pyramid has a volume of 200 cubic units and a base area of 25 square units. Find the height of the pyramid.

Answer: Rearranging the volume formula for a pyramid, we can solve for the height: height = (3 * volume) / (base area). Substituting the given values, we have height = (3 * 200) / 25 = 24 units.

### Worksheet Question 9: Volume of a Cone Inscribed in a Sphere

Question: A cone is inscribed in a sphere with a radius of 6 units. Calculate the volume of the cone.

Answer: When a cone is inscribed in a sphere, the ratio of the volume of the cone to the volume of the sphere is 1:3. Therefore, the volume of the cone is (1/3) * volume of the sphere. Since the volume of a sphere is given by V = (4/3) * π * radius^3, we have V = (1/3) * (4/3) * π * 6^3 = (8/9) * π * 216 = 192π cubic units.

### Worksheet Question 10: Solving for the Radius of a Cone

Question: A cone has a volume of 150 cubic units and a height of 9 units. Find the radius of the cone.

Answer: Rearranging the volume formula for a cone, we can solve for the radius: radius = √((3 * volume) / (π * height)). Substituting the given values, we have radius = √((3 * 150) / (π * 9)) = √(450/9π) ≈ 2.83 units (rounded to two decimal places).

### Worksheet Question 11: Volume of a Pyramid with a Hexagonal Base

Question: Calculate the volume of a pyramid with a regular hexagonal base with a side length of 6 units and a height of 10 units.

Answer: To find the volume of a pyramid with a regular hexagonal base, we need to calculate the base area. The formula for the area of a regular hexagon is A = (3√3 * side length^2) / 2. Plugging in the given value, we get A = (3√3 * 6^2) / 2 = (3√3 * 36) / 2 = 54√3 square units. Finally, we can calculate the volume using the formula V = (1/3) * base area * height: V = (1/3) * 54√3 * 10 = 180√3 cubic units.

### Worksheet Question 12: Solving for the Slant Height of a Cone

Question: A cone has a volume of 250 cubic units, a height of 8 units, and a radius of 5 units. Find the slant height of the cone.

Answer: To solve for the slant height of a cone, we can use the Pythagorean theorem. The slant height, the radius, and the height form a right triangle. Let "l" represent the slant height. By substituting the given values into the Pythagorean theorem (l^2 = r^2 + h^2), we have l^2 = 5^2 + 8^2 = 25 + 64 = 89. Taking the square root of both sides, we get l = √89 units (rounded to two decimal places).

### Worksheet Question 13: Volume of a Cone with a Hemisphere Cut Out

Question: A cone has a base radius of 6 units and a height of 10 units. A hemisphere