Since you just said A = (2,3), I think you probably mean "what's A'"? The simplest way to figure that out is to take a piece of graph paper (you can make some yourself using lined paper and drawing vertical crossbars) and drawing the X and Y axes, graphing your triangle and then graphing its reflection. That should allow you to see where A' is situated.
"The sum of the three angles in triangle ABC is equal to 180°. Hence 72 + angle ACB + angle ABC = 180 In the given isosceles triangle, angles ACB and ABC have equal measure. Hence 72 + 2 angle ABC = 180 2 angle ABC = 180 - 72 = 108 angle ABC = 54°"
"When a point of coordinates (x , y) is reflected on the x axis, its y coordinates changes sign and the coordinates become (x , - y). Hence when the vertices of the given triangle are reflected on the x axis, they become.
(1,-(2)), (2,-(-3)) and (4,-(-1))
(1,-2), (2,3) and (4,1)"
"In similar triangles, the corresponding sides have lengths in the same proportion. If h is the hypotenuse of the small traingle and H is the hypotanuse of the larger traingel, then
8 / 15 = h / H
We now use Pythagora's theorem to find h.
h2 = 82 + 62 = 100
Solve for h: h = 10
Substitute h in the above equation to find H
8 / 15 = 10 / H
8H = 150
H = 18.75