An isosceles triangle, known angle 1 is equal to 75 degrees, find the degree of angle 2

An isosceles triangle, known angle 1 is equal to 75 degrees, find the degree of angle 2

The degree of two angles of an isosceles triangle should be equal, so there are two answers. One is that the degree of angle 1 and angle 2 are equal, that is, angle 2 is also 75 degrees; the other is that the degree of the last remaining angle is equal to angle 1, then the degree of angle 2 = 180-75-75 = 30 degrees
So angle 2 is 75 degrees or 30 degrees

It is proved that an isosceles triangle with an angle equal to 60 ° is an equilateral triangle

If two angles of a triangle are equal, the opposite sides of the two angles are also equal. Geometric language: ∵ B = ∵ C ∵ AB = AC (equal angles to equal sides). Corollary 1 a triangle with three equal angles is an equilateral triangle. Geometric language: ∵ a = ∵ B = ∵ C ∵ AB = AC = B

The following figures: 1. Line segment; 2. Angle; 3. Straight line; 4. Isosceles triangle; 5. Equilateral triangle; 6. Right triangle
There must be ()
A. 3 B, 4 C, 5 d, 6 d

1,2,3,4,5 C.5