Answer:
Option A is correct
it is an acute triangle. about 0.8 foot needs to be removed from the 20-foot board to create a right triangle.
Step-by-step explanation:
She want to build a right angle frame
Then to proof it is right angle, we will apply Pythagoras theorem to the sides of the rectangle,
Since the vertical height of board is 12ft
And, the horizontal length of board is 15ft.
Then the beam that support the two beams which also form the hypotenuse is give as
(beam support)²=(horizontal board)²+(vertical board)²
x²=12²+15²
x²=144+225
x²=369
x=√369
x=19.2ft
Then the beam support is 19.2ft
To get the angle of the beam support to the horizontal
Applying trigonometric
Tanθ=opposite / adjacent
Tanθ= vertical / horizontal
Tanθ=12/15
Tanθ=0.8
θ=arctan(0.8)
θ=36.7°
This shows that it is an acute triangle.
We are told that the support beam is 20ft but this is not true because the support beam is calculated to be 19.2ft,
So, 0.8ft must be removed from the 20ft support beam to create the right angle.
Then, the best option is a
we need to cut the support beam by approx 0.8 feet to make right angle between vertical board and horizontal board.
