Answer:
- B. Quadrilateral FLAG is a parallelogram because opposite sides are parallel.
Step-by-step explanation:
<em>Refer to attached.</em>
Plot the point and connect in order FLAG.
<u>We see </u>
- FL ║ GA
- GF ║ AL
- FA and GL are not perpendicular
<u>All the above can be confirmed by calculating the slopes:</u>
- m(FL) = (3 - 5)/(6 - 1) = -2/5
- m(GA) = (1 + 1)/(-2-3) = -2/5
- These are same.
- m(GF) = (5 - 1)/(1 + 2) = 4/3
- m(AL) = (3 + 1)/(6 - 3) = 4/3
- These are same
- m(FA) = (-1 - 5)/(3 - 1) = -3
- m(GL) = (3 - 1)/(6 +2) = -1/4
- These are negative but not reciprocal
The quadrilateral is a parallelogram.
Correct choice is B
If angle BCD measures 70° then so does angle DBC (because you have formed an isoceles triangle inside the larger ΔABC and the two legs are equal so the two angles have to be equal. So we have a two 70° angles which leaves 40° for the 3rd angle, which is ∠BDC.
Since ∠BDC and ∠ADB are supplementary (180°) - that leaves 140° for ∠ADB and is our answer