Question 1155824
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Answer is <font color=red size=4>n:m</font>


Their slant heights must have the same ratio as the radii in order for the overall cones themselves to be similar. If the slant heights were not in the same ratio as the radii, then we wouldn't have similar cones.


This applies to the heights as well. Let's say they are h1 and h2. So h1:h2 = n:m also. You can use the Pythagorean theorem to find the slant heights. In effect, you'll have two similar right triangles (which are half of a vertical cross section). Then you would use the SSS (side side side) similarity theorem which says that if you have three pairs of sides in the same ratio or proportion, then the two triangles must be similar.
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