Answer:
12/sin5°
Explanation:
This angle can be calculated using the law of sine:
sin(angle)=opposite cathete/hypothenuse
sin(angle)=wall/ladder
In this exercise we want to calculate the length of the hypotenuse (ladder), so the equation is changed afterwards.
sin(angle)=wall/ladder
sin(angle)*ladder=wall
ladder=wall/sin(angle)
Now the given values are used:
ladder=wall/sin(angle)
ladder=12ft/cos(51°)