 # By Bailee and Kayla. Objectives  Find lateral areas of cylinders  Find surface areas of cylinders.

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By Bailee and Kayla

Objectives  Find lateral areas of cylinders  Find surface areas of cylinders

Lateral Areas of Cylinders  The axis of the cylinder is the segment with the endpoints that are centers of the circular bases. If the axis is also the altitude, then the cylinder is called a right cylinder. Otherwise, the cylinder is an oblique cylinder.

Tidbit of Knowledge  The net of a cylinder is composed of two congruent circles and a rectangle.  The area of this rectangle is the lateral area.  The length of the rectangle is the same as the circumference of the base, 2 r 2  So, the lateral area of a right cylinder is 2 rh base

Example  Find the lateral area of a right circular cylinder whose base has a radius of 4 inches and whose height is 6 inches. 4 6

6 4 Using the formula L=2 rh, we get… 2 x 3.14 x 6 x 4 equals 150.72 units 2

Surface Area  If a right cylinder has a surface area of T units 2, a height of h units, and the bases have radii of r units, then T= 2 rh + 2 r 2.  So basically, it’s the lateral area of the rectangle plus the area of the two bases (circles). Get it?

Example  The diameter of the base of a cylinder is 12 cm and the height is 8 cm. Find the surface area of the solid cylinder. 8cm 12cm

Using T= 2 rh + 2 r 2 Plug it in: 2 x 3.14 x 6 x 8 + 2 x 3.14 x 6 2 Equals 301.44 + 226.08 So your answer should be... 527.5 cm 2

Another Example  Find the missing radius

 How to do it

Assignment Page 657-658 # 9-20, 24, 25, 28 Have a wonderful day! ♥

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