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The true statement is (c) No; the slopes of segment EF and segment DF are not opposite reciprocals.
<h3>Right triangles </h3>Right triangles have a pair of perpendicular lines
Coordinates
The coordinates are given as:
- D = (-2,-1)
- E = (-2,2)
- F = (0,0)
Start by calculating the slopes of lines DF and EF using:
So, we have:
Also, we have:
For the triangle to be a right triangle, then the calculated slopes must be opposite reciprocals.
i.e.
By comparison, the slopes of both lines are not opposite reciprocals.
Hence, the true statement is (c)
Read more about right triangles at:
Answer:
- 60°
Step-by-step explanation:
<em>Refer to attached picture</em>
Given rectangle ABCD. Its folded shape is given as well.
It has sides a and b and diagonal d, with the angle BCD marked as α.
We need to find the value of angle AOC or BOD.
This is going to be 2α, which is easy to find out. BOD is cut by the angle bisector, each of the angles is α.
Let the area of the rectangle is A, then the folded shape has area 2/3A.
<u>The area of rectangle ABCD:</u>
- A = ab
<u>From the triangle CBD we get:</u>
- a/d = sin α ⇒ a = d sin α
- b/d = cos α ⇒ b = d cos α
<u>Then</u>
- A = d sin α * d cos α = d²sin α cos α
Now, lets find the area of the folded shape.
It is the area of the rectangle minus the area of the triangle CMB as this part is lost as part of overlap.
<u>Area of the triangle:</u>
- A = 1/2dh
<u>Since h/(d/2) = tan α ⇒ h = 1/2d tan α, the area is:</u>
- A = 1/2d*1/2d tan α = 1/4d² tan α
<u>We have the difference of the areas which is 1/3 of the area of the rectangle:</u>
- 1/3(d²sin α cos α) = 1/4d² tan α
- sin α cos α = 3/4 tan α
- sin α cos α = 3/4 sin α / cos α
- cos² α = 3/4
- cos α = √(3/4)
- cos α = √3/2
- α = arccos (√3/2)
- α = 30°
<u>The acute angle formed by the two diagonals of the rectangle is:</u>
- 2α = 2*30° = 60°
