1: In rectangle ABCD below, we have DP = PC and < BAC = 23 degrees. Find the number of degrees in < QDA + < PDC.
2: Equilateral triangle ABE is constructed inside square ABCD as shown. Find < ECD in degrees.
3: In the diagram below, we have line AB is parallel to line CD, EF = FG, < BEF = 100 degrees + x degrees, and < AEG = x degrees. Find the value of x.
4: A rectangle is made out of unit squares as shown below. Find the total area in square units of the red shaded region.
I know this is a bit unusual but I'm super sick right now and I missed my class. Any help is appreciated and huge thanks to anyone with the answers!
Mmmmm....let's see..
1) Since BAC = 23, then angle DAQ will be complementary to this = 90 - 23 = 67
And QDA = 90 - DAQ = 23
And since DP = PC, then in triangle DPC.....angle DCP = angle PDC
But......since tranversal AC cuts parallels DC and AB....then angle BAC = angle DCP = 23
So....PDC also = 23
So....
QDA + PDC = 23 + 23 = 46°
3)
Because transversal EF cuts parallels AB, CD.....then angle BEF = angle GFE
And since EF = FG.....then angles FEG and EGF are equal
So.....angle FEG = [ 180 - (100 +x) ] / 2 = (80 - x)/2
And angles BEF + FEG + AEG = 180
Sustituting....we have that
(100 + x) + (80 - x) / 2 + x = 180 multiply through by 2
2(100 + x) + 80 - x + 2x = 360 simplify
200 +2x + 80 - x + 2x = 360
280 + 3x = 360 subtract 280 from both sides
3x = 80 divide both sides by 3
x = 80/3 ° ≈ 26.66°
4) This one isn't too difficult
The total area of the rectangle is 7 x 5 = 35 units^2 (1)
The white triangle is obtuse.....
The base of this triangle......sitting on the "bottom" of the rectangle = 2 units
The altitude occurs outside the triangle and is = 5 units
So....the area of this triangle is (1/2) base * altitude = (1/2) (2) (5) = 5 units^2 (2)
So.....the red area is just the difference of (1) and (2) =
35 - 5 = 30 units^2
P.S. - hope you're feeling better !!!
Thank you so much! I actually found the transcript of my class from a friend so I'm covered on that front (phew) All your answers were so helpful!
2) Note that the side of the equilateral triangle = Side of the square
So.....draw EC
And in triangle ECB, EB = CB and angle CBE = 30°
But ....since EB = CB, the angles opposite those sides, ECB and CEB will be equal
And either will be = (180 - 30) / 2 = 150 / 2 = 75°
So....angle ECB = 75°
So.....angle ECD will be complementary to this = 15°