Question

ABC is a triangle right angled at A and D is a point on BC such that AD Ʇ BC. Show that AD2 = BD x DC. please answer fast URGENT

Answer 1

The answer is below

Explanation:

Pythagoras theorem states that for a right angled triangle, the square of the hypotenuse side is equal to the sum of the square of the remaining sides. The hypotenuse is the longest side (that is side opposite to the 90° angle).

In right angle triangle ABD:

AB² = AD² + BD² (1)

In right angle triangle ACD:

AC² = AD² + CD² (2)

Also:

AC² + AB² = BC² (3)

But BC = BD + CD

AC² + AB² = (BD + CD)² (4)

Adding equation 1 and 2 gives:

AB² + AC² = (AD² + BD²) + (AD² + CD²)

AB² + AC² = 2AD² + BD² + CD²

substituting AC² + AB² = (BD + CD)²:

(BD + CD)² = 2AD² + BD² + CD²

BD² + 2(BD)(CD)+ CD² = 2AD² + BD² + CD²

2AD² = 2(BD)(CD)

AD² = BD * CD