Mission 7Mission 7

Mission for 7:Mission for 7: To successfully find the surface area of a sphere.

VocabularyVocabulary:: surface area, sphere

FormulaFormula:: A = 4 r2

Surface area ReviewSurface area Review

Recall that surface area is the measure of the total surface of a 3-dimensional shape. For example, if you were hired to paint golf balls green, you would bepainting the surface of the golf ball. The measure of the area that youpainted is surface area.

Formula for a SphereFormula for a Sphere

The formula for the surface area of a sphere is

where SA is the surface area and r is the radius of the sphere.

This is how we do it!This is how we do it!Find the surface area of a beach ball with radius of 50 cm.

The formula for surface area of a sphere (beach ball) is :

SA = 4 r2

= 4 (50)2 Therefore, the surface area is 31415.7 cm2

Mi Problem es Mi Problem es su Problemsu Problem

What is the radius of a bowling ball with a surface area of 225 cm2?

Right On!Right On!

Wow. . . Wow. . . And I And I thought I thought I had had all the all the answers!answers!

I guess I guess you’re just you’re just a pro now!a pro now!

Don’t look Don’t look in the in the newspaper newspaper for the for the answer. answer. Just click Just click on on Muddler.Muddler.

Here is your Answer...Here is your Answer...

SA = 4 r 2

225 = 4 r 2

17.9 = r 2

4.23 = r

Looks like we made it!

Click on Box Click on Box Muddler if you Muddler if you love Geometry!love Geometry!

Exit!Exit!

I hope you’ve I hope you’ve enjoyed enjoyed the show. the show.