Answer:
number 2,3,5 are correct answer
Reflection about the y-axis is according to the rule
(x,y)->(-x,y)
Therefore F(x,y) -> F'(-x,y)
The distance between F' and F is (-x,y)-(x,y)=-2x, or the positive distance is 2x.
Is it a triangle??? Or a square??
First calculate the missing angle

. By knowing all angles in triangle have a sum of 180°.


Now we required to use angle functions in a right triangle. The cosine of

is equal to the relation of side

and hypotenuse

.
Now we solve this for hypotenuse.


Now put in the numbers.

So we know the length of hypotenuse and length of side

therefore side

can be calculated using Pythagorean theorem:

.
Solve for side

.



So there you go. If you have any questions feel free to ask.
r3t40