>>14259816>tell your brother that opposite angles are equali'd say it's important to understand that beyond "well that's just the rule".
imagine you had two perpendicular lines, with 90 on all 4 angles.
if you tilted the vertical line slightly, 1 degree, what happens?
you have closed the top left by 1 degree, and also closed the bottom right by 1 degree.
you also opened the top right by 1 degree, and opened the bottom left by 1 degree.
at the extreme, this same symmetry happens. so at any angle of the two lines, you've got this same behavior of the opposite angles.
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beyond that, you could imagine if you had two horizontal parallel lines, and do the same exact exercise.
the behavior is the same. with the 90 degree angles it's obvious.
as the angle of the "vertical line" changes, it sort of "shifts" where the "center" of the angles are, but they're still exactly the same.
