1. 11.3 Pyramids and Cones

3. Hahahaha…..as if they’d all be that easy!
Triangular pyramid with base area 9 in and height 4 in
Hahahaha…..as if they’d
all be that easy!

4. Slant height

5. Ex 2) Square pyramid with side length 4 in and slant height 6 in

6. Ex 4) Find the Volume

9. Example 5
Find the volume of a cone with radius 7 cm and height 15 cm. Give your answers both in terms of  and rounded to the nearest tenth.
Volume of a pyramid
Substitute 7 for r and 15 for h.
= 245 cm3 ≈ cm3
Simplify.

10. Example 6
Find the volume of a cone.
Step 1 Use the Pythagorean Theorem to find the height.
162 + h2 = 342
Pythagorean Theorem
h2 = 900
Subtract 162 from both sides.
h = 30
Take the square root of both sides.

11. Example 7
Find the volume of the composite figure. Round to the nearest tenth.
The volume of the upper cone is

12. Find the volume of the composite figure. Round to the nearest tenth.
The volume of the cylinder is
Vcylinder = r2h = (21)2(35)=15,435 cm3.
The volume of the lower cone is
The volume of the figure is the sum of the volumes.
V = 5145 + 15,435 + 5,880 = 26,460  83,126.5 cm3

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