how does BC=6m

in the video of lesson 8 of ch-6

we are given, hypotenuse = AC = length of the ladder = 10 m

 perpendicular = AB = length of the wall = 8m

now, we have to find the base BC.

We know that in a right triangle square of the hypotenuse is equal to sum of the squares of the other two sides.

so, AC² = AB² + BC²  [Pythagoras Theorem]

BC² = AC²- AB²

BC² = 100 - 64 = 36

taking square root both sides, we get 

BC = 6 m