Answer:
8
Step-by-step explanation:
Answer:
AAS is an acronym for Angle-Angle-Side. It basically means that if two angles and a nonincluded side of one triangle are congruent to two angles and the corresponding nonincluded side of a second triangle, then the two triangles are congruent. SAS is an acronym for Side-Angle-Side. It means that if two sides and the included angle of one triangle are congruent to two sides and the included angle of a second triangle, then the two triangles are congruent. SSS is an acronym for Side-Side-Side. It means that if three sides of one triangle are congruent to three sides of a second triangle, then the two triangles are congruent. ASA is an acronym for Angle-Side-Angle. It means that if two angles and the included side of one triangle are congruent to two angles and the included side of a second triangle, then the two triangles are congruent.
In the problem, we know that the corresponding sides of both triangles are congruent to each other, so those would be given. The third side of each triangle would also be congruent because of reflexive property. Reflexive property means that the two triangles share a line segment. So, the answer would be SSS.
OK, so the graph is a parabola, with points x=0,y=0; x=6,y=-9; and x=12,y=0
Because the roots of the equation are 0 and 12, we know the formula is therefore of the form
y = ax(x - 12), for some a
So put in x = 6
-9 = 6a(-6)
9 = 36a
a = 1/4
So the parabola has a curve y = x(x-12) / 4, which can also be written y = 0.25x² - 3x
The gradient of this is dy/dx = 0.5x - 3
The key property of a parabolic dish is that it focuses radio waves travelling parallel to the y axis to a single point. So we should arrive at the same focal point no matter what point we chose to look at. So we can pick any point we like - e.g. the point x = 4, y = -8
Gradient of the parabolic mirror at x = 4 is -1
So the gradient of the normal to the mirror at x = 4 is therefore 1.
Radio waves initially travelling vertically downwards are reflected about the normal - which has a gradient of 1, so they're reflected so that they are travelling horizontally. So they arrive parallel to the y axis, and leave parallel to the x axis.
So the focal point is at y = -8, i.e. 1 metre above the back of the dish.