Given two poles of heights 6 m and 11 m stand vertically upright on a plane ground. Distance between their foot is 12 m.

Let CD be the pole with height 6 m. AB is the pole with height 11m and DB = 12 m

Let us assume a point E on the pole AB which is 6m from the base of AB.

Hence AE = AB – 6 = 11 – 6 = 5m

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

Now, in right triangle AEC,

⇒ AC² = AE² + EC²

Since CDEB forms a rectangle and opposite sides of rectangle are equal,

⇒ AC² = 5² + 12²

= 25 + 144

= 169

⇒ AC = 13

∴ The distance between their tops is 13 m.