Henry Ernest Dudeney/Puzzles and Curious Problems/240 - Counting the Triangles/Solution

by : $240$

 * Counting the Triangles

Solution
There are:
 * $5$ triangles of the form $\triangle ADC$
 * $5$ triangles of the form $\triangle AEB$
 * $5$ triangles of the form $\triangle ABF$
 * $5$ triangles of the form $\triangle AKF$
 * $10$ triangles of the form $\triangle AKB$
 * $5$ triangles of the form $\triangle ADG$

That seems to be all of them.

Thus there are $35$ triangles altogether.