Question

The base angles of an isosceles triangle cannot ne right or obtuse. Why?

Answer 1

We know that the base angles of an isosceles triangle are equal

let the the equal angles be x and the third and be y

(i)base angle is 90°

2x+y

= 2 * 90+y

= 180°+y

this is greater than 180° thus it is not possible

(ii) base angles are obtuse

obtuse angle is greater than 90°

then

x > 180°

2x>180°

2x+y>180°

thus it is not possible