Question

In the the diagram to the right, sphere O with radius 20 cm is intersected by a plane 12 cm from center O. Find theradius of the cross section O A.

Answer 1

Question:

Solution:

The radius of the cross-section is the adjacent side of the right triangle inside the sphere. We can find this side if we apply the Pythagoras theorem:

$r\text{ = }\sqrt[]{20^2-12^2}$

this is equivalent to:

$r\text{ = }\sqrt[]{20^2-12^2}\text{ = 16}$

then, the correct solution would be:

$r\text{ = 16}$