Answer:
Correct option: first one -> 9.46 feet long
Explanation:
To find the length of the board for her ramp, we just need to use the sine relation of its angle with the ground.
The opposite side to the angle is the height of the ramp, and the hypotenuse of the triangle formed is the length of the board. So, we have that:
sin(25°) = height / length
0.4226 = 4 / length
length = 4 / 0.4226
length = 9.4652 feet
So the length of the board should be 9.46 feet (correct option: first one)