Since you did not provide a diagram, I made one for easier reference. You are asking what kind of triangle is the one shaded in red. Since a rectangle has two sets of congruent sides, their diagonals are also equal. When two diagonals intersect each other, they make 4 congruent sides. Thus, the triangle is an isosceles triangle, since it has two equal sides ST and TR.
Answer:
The fourth
Step-by-step explanation:
It has 4 terms
Their brother will be 67 years old because when they were six their brother was 3. They were three years apart.
So since the vertex falls onto the axis of symmetry, we can just solve for that to get the x-coordinate of both equations. The equation for the axis of symmetry is 
, with b = x coefficient and a = x^2 coefficient. Our equations can be solved as such:
y = 2x^2 − 4x + 12: 
y = 4x^2 + 8x + 3: 
In short, the vertex x-coordinate's of y = 2x^2 − 4x + 12 is 1 while the vertex's x-coordinate of y = 4x^2 + 8x + 3 is -1.
