How can the given figure be used to explain the sum of the angle measures of a triangle? The image shows three figures. The first figures is a triangle with angles labeled 1, 2, and 3. An arrow points from this figure to the right to the next figure. The next figure is a triangle with angles labeled 1, 2, and 3. A copy of that triangle is rotated counterclockwise so that angles 2 and 3 become adjacent. An arrow points from this figure to the right to the next figure. The next figure is a triangle with angles labeled 1, 2, and 3. A copy of that triangle is rotated counterclockwise so that angles 2 and 3 become adjacent. Another copy of the original triangle is rotated clockwise so that angles 1 and 2 become adjacent. Select from the drop-down menus to correctly complete each statement. A triangle has angles 1, 2, and 3. Make a copy of the triangle and rotate the copy counterclockwise so that angle 3 is adjacent to Choose... . Then, make another copy of the triangle and rotate this copy clockwise so that angle 1 is adjacent to Choose... . The three angles form Choose... angle. Therefore, the sum of the angle measures of a triangle Choose... the measure of a straight angle. Choose... angle has a measure of 180°. Therefore, the sum of the angle measures of a Choose... equals 180°.