Question

Line is intersected by line , as shown in the diagram below. Based on the diagram, which of the following equations must be true? *

∠1 + ∠2 = 180°
∠1 + ∠3 = 180°
∠2 + ∠3 = 90°
∠2 + ∠4 = 90°

Answer 1

i think it is the first one

Answer 2

From what I have seen, it's: ∠1 + ∠2 = 180°