SOLUTION: The vertices of parallelogram ABCD are A(0,0), B(7,0), (12,8), and D(5,8). Find, to the nearest degree the measure of angle DAB. I don't get this at all! All I know is that the

Algebra ->  Angles -> SOLUTION: The vertices of parallelogram ABCD are A(0,0), B(7,0), (12,8), and D(5,8). Find, to the nearest degree the measure of angle DAB. I don't get this at all! All I know is that the      Log On


   



Question 143302: The vertices of parallelogram ABCD are A(0,0), B(7,0), (12,8), and D(5,8). Find, to the nearest degree the measure of angle DAB.
I don't get this at all! All I know is that the measure of side AB is 7 and the measure of side CD is also 7.

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
The vertices of parallelogram ABCD are
A(0,0), B(7,0), (12,8), and D(5,8). Find,
to the nearest degree the measure of angle DAB.
I don't get this at all! All I know is that the
measure of side AB is 7 and the measure of side CD is also 7.

 

First draw a perpendicular DE to AB

 

Because D's coordinates are (5,8), we know that AE=5, DE=8

ADE is a right triangle.

DE is the side opposite angle DAB and
AE is the side adjacent angle DAB,

and since TANGENT+=+%28OPPOSITE%29%2F%28ADJACENT%29

tan%28DAB%29+=+%28DE%29%2F%28AE%29+=+8%2F5+=+1.6

Now, with calculator in DEGREE mode, use the TAN%5E%28-1%29
key and get 57.99461679° which to the nearest degree is 58°

Edwin