By: Ashley, Kelsey, Devin, Jarred, Shaq

Surface area formula

SA=4πr^2 Finding a radius

EX. SA=30in plug it back into formula

SA=4πr^2

30in=4πr^2 divide by 4π to both sides

2.38in=r^2 then your Square root

2.38in=√r^2

R=1.55in

Now plugging it back into the formula to find SA

SA=4πr^2

SA=4π(1.55in)^2

SA=30in^2 Remember to square your units cause its SA

Volume Formula

V=4/3πr^3 Finding the radiusEX. V=60cmV=4/3πr^3 Plug in 60 for V60cm=4/3πr^3 Divide by 4/3π to both sides14.3239cm=r^3 Then you Cube root2.42cm=r

Plugging It back in.V=4/3πr^3V=4/3π(2.42)^3V=60

And remember if you have a diameter of 16 or any number to find radius just divide by 2

MM2G4B

Determining the effect on surface area and volume of changing the radius of a sphere.

Surface area

When you double the radius the surface area changes by a multiple of 4

So, when you triple the radius the surface area changes by a multiple of 9

Double (2) radius X4

Triple (3) radius X9

Volume

If you double the radius the volume changes to a multiple of 8

So, if you triple the radius the volume changes to a multiple of 27

Double (2) radius X8

Triple (3) radius X27

Examples of surface area

SA=4πr²

R=1

SA=4π(1)²

SA=4π1

SA=4π

SA=12.6

Double it R=2

SA=4π(2)²

SA=4π4

SA=16π

SA=50.3

12.6 x 4

SA=50.4

Examples of Volume

V=4πr³/3

R=4

V=4π(4)³/3

V=85.3

Double it r=8

V=4π(8)³/3

V=682.7

V=85.3 x 8=682.4