If a ladder is at a 50 degree angle and the top hits the wall 9 feet high, how long does the ladder have to be?

138.96

I don't know, but a constipated mathematician works it out with a pencil.

11.75 feet also known as 11 ft 9 inches

not for a survey person

I don't care.

sine of the angle (right angle triangle) = opposite side/hypotenuse(ladder in this case). So sine 50 degrees = .766. .766 = 9/ladder, or ladder = 9/.766. As others said 11' 9".

50 degrees to the wall or the ground?

My answer is for 50 degrees to the ground. That's the normal way a ladder angle is specified in the safety instructions, but the OP didn't say so it's a good question.

A 14 footer will work. You want it to be higher than the wall

+3' for safety

Depends.Is it OK if I put a hole in the sheet rock on the ceiling?

If your inside you need drywaller stilts

12 FEET

Couple are right but you have to show your work !!

Ladder needs to be longer than that. It should extend above the wall a couple feet. Your math wont work

Truthfully the angle is to shallow to be safe also. Bottom of the ladder needs to be closer to the wall

139" should be fine

I assumed 50 degrees from the ceiling if it's the floor- here's your length in inches.

Thank you everybody. Lots of smart trappers here.