" 1.Define a triangle."

Define : Similar triangles

Define E and Delta

How do we define perimeter of a triangle?

Let T be set of all triangle in the Euclidean plane , and let a relation R on T be defined as aRb if a is congruent to b,AA "a",b inT . Then, R is ....

Show that the relation R defined in the set A of all triangles as : R = [(T_1, T_2): T_1 and T_2 are similar triangles} is an equivalence relation .

Define an equivalence relation. Show that the relation similarity on the set of all triangles in a plene is an equivalence relation.

In an acute angled triangle A B C , a semicircle with radius r_a is constructed with its base on BC and tangent to the other two sides. r_b a n dr_c are defined similarly. If r is the radius of the incircle of triangle ABC then prove that 2/r=1/(r_a)+1/(r_b)+1/(r_c)dot