If line rt is rotated about the origin such that its image line r't' is parallel to it, then the angle of rotation would be which of the following?
a)90 °
b)180 °
c)270 °
d)360 °

Imagine an arrow pointing directly to the east. If you rotate it 180 degrees, then it ends up pointing directly west. Both arrows will form the same straight line if you join them up together at the endpoints. This idea of rotating an arrow can also apply to rotating lines as well.

5050 i think

step-by-step explanation:

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15