C1 parallelogram graph question

It's a parrallelogram so It can't be a right angle

...I, say what? A rectangle is a parallelogram... what are the angles in a rectangle?

hi, I am a bit stuck on part b and c of this question. To solve this, apparently line Ad is perpendicular to l1 but how can that be as the angle in between isn't a right angle. I know that l1 and l2 are parallel and the other two lines are as well. Thanks.

In answer to your question, AD is not perpendicular to $\ell_1$, either you are reading wrong or the markscheme is wrong. What I suspect is happening is that you are reading wrong and that the mark scheme is finding a line that passes through A and is perpendicular to $\ell_1$ but this does not imply that the line also passes through D.

Yeah , sorry my mistake. I got confused that's why. So this is what I think is happening: find the perpendicular line to L1 going through A. Then find the point of intersection with L2. Then work out the distance between A and the point of intersection? Right?

Yes.

So this distance is the same as the length of AD/ bc ? Because for part c, they used length of AB and the distance found in the previous part of the question.