Question

prove that the diagonal of an isosceles trapezium are equal

Answer 1

Hey! Here's your answer :-

AB = CD ---------->  Isosceles trapezium

Angle A = Angle D ---------->  Isosceles trapezium

AD = AD -----------> Self-congruence

Triangle ABD is congruent to Triangle DCA by SAS test.

By CSCT,

AC = BD

Hence proved!

Hope this helps! :)