5x+9 = 10x-9
Take 5x from both sides
9 = 5x-9
Add 9 to both sides
18 = 5x
Divide by 5
3.6=x
Answer: option <span>D) y=x, x-axis, y=x, y-axis</span>.
I first thought it was the option C) and I tried with it but it was wrong. This is how I dit it.
Option C step by step:
<span>1) Reflection over the x - axis => point with coordinates (a,b) is transformed into point with coordinates (a, -b)
2) Reflection over the line y = x => point with coordinates (a, -b) is transformed into point with coordinates (-b,a)
3) New feflection over the x - axis => (-b,a) transforms into (-b, -a)
4) New reflection over the line y = x => (-b,-a) transforms into (-a,-b)
Which shows it is not the option C).
Then I probed with option D. Step by step:
1) Reflection over the line y = x => (a,b) → (b,a)
2) Reflection over the x-axis => (b,a) → (b,-a)
3) Reflection over the line y = x => (b,-a) → (-a,b)
4) Reflection over the y-axis => (-a,b) → (a,b).
So, this set of reflections, given by the option D) transforms any point into itself, which proofs that the option D) is the right answer.
</span>
<span>First of all in order to find the exact value by using a half angle identity we will do
cos(5π divided by 12)
=cos (5π divided by 6) divided by 2
= ± Under root[(1+cos (5π divided by 6) divided by 2]
Now we will consider + sign because 5π divided by 12 is in quadrant. where cos>0
so the solution is [(1- Under root 3 divided by 2) divided by 2]
We will ignore the negative sign
I hope it helped.</span>
A and B ............................
