Geometry

Question

Which of the triangles is an isosceles triangle having the three angles :

• A. $40^{\circ},50^{\circ},90^{\circ}$
• B. $30^{\circ},60^{\circ},90^{\circ}$
• C. $45^{\circ},45^{\circ},90^{\circ}$
• D. $35^{\circ},55^{\circ},90^{\circ}$

Answer 1

An Isosceles (iso means same and skelos means leg which tells same leg )triangle is an triangle with two equal sides (as shown in the above image , where equal sides are marked by a & the remaining side are marked by b). And we know when two sides are equal, two angles are also equal. So, Isosceles Triangle has two equal sides with two equal angles.

∴ Among the above options only option C) is having two equal angles.

So, Answer will be Option C). 

Answer 2

Option c <45,45,90>

• An isosceles triangle  both two equal sides and two equal angles.