kept on a stool

ladder wall and distance of the stool from wall makes an right angled triangle where one side is 9

if its a 3,4,5 triangle then other sides will be 12 and 15

if the side of wall is 12 then total height of wall..include the stool height=length of ladder=15

Ans option C 15

Can someone verify if this method works. I got the same answer as liferocks, albeit it was negative.

The ladder is leaning on the wall and the floor and the wall make a right angle.

height of slanted ladder = a
Wall height = a + 3

pythagorean theorem:

9^2 + (a + 3)^2 = a^2 (FOIL)

81 + a^2 + 6a + 9 = a^2 (Subtract a^2)

81 + 6a + 9 = 0 (Subtract 90)

6a = -90

a = -15

Ashish8 wrote:Can someone verify if this method works. I got the same answer as liferocks, albeit it was negative.

The ladder is leaning on the wall and the floor and the wall make a right angle.

height of slanted ladder = a
Wall height = a + 3

pythagorean theorem:

9^2 + (a + 3)^2 = a^2 (FOIL)

81 + a^2 + 6a + 9 = a^2 (Subtract a^2)

81 + 6a + 9 = 0 (Subtract 90)

6a = -90

a = -15

just a small correction
wall height is a and from pythagororus theorem we get

9^2+(a-3)^2=a^2

h² = 9² + (h-3)²
6h = 90
h = 15