A flight of 13 steps from the ground to a platform of height 3 m is to be carpeted. The steps are all equal and have tread a and rise b. The staircase starts from a point on the ground horizontally 4 m away from the edge of the platform as shown.
Assuming that the width of the carpet is adequate, what is the length of the carpet (in meter) needed to cover all the steps ?
1
7
2
5
3
(3a + 4b)/√13
4
\(\rm \sqrt{13}(a+b)\)