Question

If the combined area of the white and orange regions is 100π, what is the area of ONLY the orange region?
A) 16π
B) 36π
C) 64π
D) 96π

Answer 1

http://www.usatestprep.com/modules/gallery/files/60/6056/6056.png

Answer 2

Formula for area of a circle
\(=\pi~r^{2}\)

Answer 3

Total combined area
\(=100~\pi\)

Answer 4

\(\pi~6^{2}+\pi~r^{2}=100\pi\)

Answer 5

\(36\pi+\pi~r^{2}=100\pi\)

Answer 6

Factorise pi
\(\pi(36+r^{2})=100\pi\)

Answer 7

Divide both sides by pi
\(36+r^{2}=100\)

Answer 8

Subtract both sides by 36
\(r^{2}=64\)

Answer 9

Square root both sides
\(r=\pm8\)

Answer 10

i realised that i give the answer... xD
Sorry...

Answer 11

okay,can u tell me why r=-8 cannot be accepted but r=8 can be accepted? @Hanna

Answer 12

because its a negative?

Answer 13

yep,that's right!
area can't hv negative value... :)

Answer 14

okay thx <3

Answer 15

Np ^_^