Each face of a pyramid is an isosceles triangle with a 74° vertex angle. what are the measures of the base angles?

Os ângulos da base são congruentes...
A soma dos ângulos internos do triângulo é 180º
x + x + 74 = 180
2x = 180 - 74
2x = 106
x = 106/2
x = 53º (ângulos da base)

Best answer that i found on yahoo ok   set :   x= length of 2nd piece in cm  x- 3= length of 1st piece in cm  x-4= length of 3rd piece in cm  then since you know they all came from the 20 cm ribbon you add them together and set them equal to 20x+ x-3 +x-4 = 20  3x - 7= 20  3x= 27  x= 9  the shortest piece is the third piece which is x- 4  x-4  9-4 = 5  the length of the smallest piece is 5 cm.  the other lengths are  9 cm  6 cm