Answer:
The ladder is 11,7ft long.
Step-by-step explanation:
This angle can be calculated using the law of cosines:
cos(angle)=opposite cathete/hypothenuse
cos(angle)=ground/ladder
In this exercise we want to calculate the length of the hypotenuse (ladder), so the equation is changed afterwards.
cos(angle)=ground/ladder
cos(angle)*ladder=ground
ladder=ground/cos(angle)
Now the given values are used:
ladder=ground/cos(angle)
ladder=4ft/cos(70°)
ladder=11,7ft
The ladder is 11,7ft long.