Answer:
Given: In triangle ABC , AD is drawn perpendicular to BC.
Since AD is drawn perpendicular to BC, it creates two right triangles: ADB and ADC.
Prove that:
Pythagoras triangle for right angle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the legs.
In a right angle triangle ADB;
[By Pythagoras theorem]
or
.......[1]
Now, in right angle triangle ADC;
[By Pythagoras theorem]
or we can write this as;
......[2]
Substituting the equation [1] in [2] we get;
hence proved!
