Question

show that AD=AB.pls ans fast ⏩⏩ ​

Answer 1

In AABC, ZABC=2ACB=0 (let) [as AB=AC

AABC is isosceles]

Now, we know that, in an isosceles A, the base angles are acute as only one obtuse angle can exist in a A.

Now ZACD=

180°-ZACB

[linear pair]

so, in AACD, ZACD is the largest angle.

so, ZACD > ZADC

so, from triangle inequality, side opposite to the larger angle is gt the side opposite to the smaller angle,

SO, AD > AC

but, AC=AB [given]

so, AD > AB

Quad Erat Demonstrandum.