Question

I barely just learned this and our teacher just told us the shapes and it’s rule but never explain on finding the angles and want it’s asking for.

Answer 1

as i see from the picture, this lecture mainly taught you relationship of the angles in a specific condition

such as

corresponding angles, AB//CD ,

alternate angles, AB//CD ,

interior angles, AB//CD

In my figure, a+b is always equal to 180degree if the X line is straight

a+b=180

imagine there is Y line which is parallel to the X line

c+d=180

a=c, b=d because y line and x line is parallel (corresponding angles,X//Y)

then b+a=180, substitute c as a, b+c=180(interior angles, X//Y)