Step by step
The question
Question: in a right triangle the median to the hypotenuse is 6: find the hypotenuse B C.
1 Use the semicircle rule
The right angle is at A.
The median A M goes to M, the middle of the hypotenuse B C.
Draw the circle with B C as its diameter.
The angle in a semicircle is 90°, so A is on this circle too.
M is the center.
M A, M B and M C are all radii: all the same length.
2 Double the median
The diameter is twice the radius: 12.
Careful!
This works for the median to the hypotenuse of a right triangle.
Not for any median.
3 Check
Let's check: M B and M C are 6 each, and together they make B C, 12.
So it is right!
Let's look back.
First: use the semicircle rule.
Then: double the median.
Last: check.