Answer. First option: -1
Solution:
We have a triangle, and we know two angles of 60° each one. We can find the third angle A, using:
A+B+C=180°, with B=60° and C=60°:
A+60°+60°=180°
Solving for A: Adding similar terms:
A+120°=180°
Subtracting 120° both sides of the equation:
A+120°-120°=180°-120°
A=60°
The third angle A is 60° too, then the triangle has three equal angles of 60° each one, and it is an equillateral triangle, thus its three sides must be congruents:
2y+6=4=2x-3
We need to find the value of y, then using the first equality:
2y+6=4
Solving for y: Subtracting 6 both sides of the equation:
2y+6-6=4-6
2y=-2
Diniding both sides of the equation by 2:
2y/2=-2/2
y=-1
