(1) A circle centered at P with radius 10 and a circle centered at Q with radius 8 are externally tangent. Find PQ.
(2) How many common external tangents do two circles have?
(1) A circle centered at P with radius 10 and a circle centered at Q with radius 8 are externally tangent. Find PQ.
If you'll draw this, you'll easily see that it's the sum of the two radii, namely 10 + 8 = 18
(2) How many common external tangents do two circles have?
You didn't say if this is specifically in reference to the two circles in (1). Well, anyway:
If two circles are overlapping, they can have 2 common tangents.
If two circles are externally tangent, they can have 3 common tangents.
If two circles are some distance apart, they can have 4 common tangents.
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