### Lines and Triangles

goals
If $S$ is any point in the interior of $\Delta PQR$, prove that $(SQ + SR) < (PQ + PR)$.
In $\Delta ABC, \, \angle A = 90^o , \, AB = 5$ cm and $BC = 13$ cm. Find the radius of the incircle of $\Delta ABC$.
The sides of a triangle are $6$ cm, $11$ cm and $15$ cm. Construct incircle and find the radius of the triangle.
In right triangle ABC, the right angle is at C, M is the mid-point of hypotenuse AB. C is joined to M and produced to a point D such that DM = CM. Point D is joined to point) B (see figure).
When we write $\angle A = \angle B$ , we actually mean ______________.