It is known that ∠ 1 and ∠ 2 are opposite vertex angles, and ∠ 1 and ∠ 3 are adjacent complementary angles, then ∠ 2 + 3 is equal to? 2. When two lines intersect, there are two pairs of vertex angles. When three lines intersect, there are six pairs of vertex angles. So how many pairs of vertex angles are there when n lines intersect?

It is known that ∠ 1 and ∠ 2 are opposite vertex angles, and ∠ 1 and ∠ 3 are adjacent complementary angles, then ∠ 2 + 3 is equal to? 2. When two lines intersect, there are two pairs of vertex angles. When three lines intersect, there are six pairs of vertex angles. So how many pairs of vertex angles are there when n lines intersect?

one hundred and eighty

It is known that ∠ 1 and ∠ α are antiparietal angles, and ∠ α and ∠ 3 are complementary angles. If ∠ 1 = 30 °, then ∠ 3=______ ．

∵∠ 1 and ∠ α are opposite vertex angles, ∵∠ α = ∠ 1 = 30 °, ∵∠ α and ∠ 3 are adjacent complementary angles, ∵∠ 3 = 180 ° - α = 180 ° - 30 ° = 150 °. So the answer is: 150 °

If ∠ 1 and ∠ 2 are complementary angles to each other, then ∠ 1 plus ∠ 2 is equal to ∠ 1 ∠ 3 (the second is comparative size) if ∠ 1 and ∠ 3 are opposite vertex angles to each other

①：180°
∵ two corners have a common edge, and the other edge of them is the opposite extension of each other. The two corners with this relationship are called adjacent complementary angles
And: after removing the common edge, the extension line plus a common vertex is a flat angle
∴∠1+∠2=180°
②：∠1=∠3
∵ two opposite angles are equal (this is a mathematical concept)
∴∠1=∠3