Glencoe Math: Course 3, Volume 2
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Glencoe Math: Course 3, Volume 2 View details
5. Surface Area of Cones
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Exercise 19 Page 637

The lateral area of a right cone is half the product of the circumference of the base and the slant height.

62.8m^2

Practice makes perfect

We want to find the lateral area of the given cone.

To do so, we must know that the lateral area of a right cone is half the product of the circumference of the base and the slant height. L.A.=1/2* 2π r* l ⇔ L.A.=π rl In this formula, r is the radius and l is the slant height of the cone. Since we know that the diameter d is equal to 8, we can divide it by 2 and get the radius of the base. r=8/2 ⇒ r= 4 With this information we are able to calculate the lateral area of the cone. To do so, we will substitute r= 4 and l= 5 into the formula for the lateral area. Let's do it!

L.A.=Ï€ rl
L.A.=Ï€ ( 4)( 5)
L.A.=Ï€ (20)
L.A.=20Ï€
L.A.=62.831853...
L.A.≈ 62.8

The lateral area of the given cone, to the nearest tenth, is 62.8 square meters.