Giving brainliest to whoever answers well & first.  ∠c and ∠d are vertical angles with m∠c=−2x+90 and m∠d=x−30 . what is m∠d ? enter your answer in the box.

Which of the following parabolas opens down?

With number 11 ( show how you got the answer)

5, 6, 10 question: a. determine whether the side lengths form a triangle. (explain your reasoning) b. if it is a triangle, determine whether it is a right, acute, or obtuse triangle. (show your work)