Ahome has 3 stairs leading to its front door with each stair having a vertical height of 10 inches and a horizontal tread length of 18 inches. when a new refrigerator is delivered to the home, the delivery people lay down a wooden plank over the stairs so that they can roll the refrigerator up the plank. what is the answer ? ?

61.77 inches

Step-by-step explanation:

Please refer to the picture attached. Here we can see that the total length of the plank , is the sum of the three hypotenuses.

Hence we have to determine, the hypotenuse on one stair whose height is 10 and width is 18 inches

We know that the Hypotenuse is given by the formula

here a = 18 and b = 10

Hence length of one hypotenuse is 20.59 inches. Thus that of 3 hypotenuses will be 20.59*3 = 61.77

Therefore Delivery guys need a 61.77 inches long plank to roll up the refrigerator