We know that the formula for the area of a rectangle is:
We know that the area is 165. Now we need to solve for the dimensions.
Let the width of the rectangle be "

"
Then the length of the rectangle is
Substitute.
Multiply the terms.
Bring the 156 over.
We have to use the quadratic formula to solve this now. Let us restate it:

Now I'm going to fast forward this because all the rest is boring stuff and substitution. The answer is:

Since we cannot have a negative answer, we must cancel out the other answer, which I did not include.
Hope this helped! :)
~Cam943, Junior Moderator
Answer:
a=6 - isosceles triangle and special triangle 90-45-45
b= 6^2+6^2=72
sqrroot 72 = 8.48528137424
X would be 39
Add the two angles to get 90+51 =141
Then subtract 180 from 141 to get 39