# SAT help

• Oct 2nd 2010, 07:22 AM
abhilash
SAT help
I need help with this attached question from my SAT question. Please help me.
• Oct 2nd 2010, 07:41 AM
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Quote:

Originally Posted by abhilash
I need help with this attached question from my SAT question. Please help me.

Call area of large circle A1, area of medium circle A2, and area of small circle A3.

Do you see why it's A1 - A2 + A3?
• Oct 2nd 2010, 07:42 AM
skeeter
sketch a y-axis that cuts the large circle vertically thru its center, then take the lower large semicircle and reflect it (flip it) over the y-axis

can you see that the unshaded area = $\pi \cdot 2^2 - \pi \cdot 1^2$ ?

shaded area = area of large circle - unshaded area