Can anyone help me on algebra one it’s nine grade level

Which of the following vectors are orthogonal to (2,1)? check all that apply

Which statement is true about the extreme value of the given quadratic equation? a. the equation has a maximum value with a y-coordinate of -21. b. the equation has a maximum value with a y-coordinate of -27. c. the equation has a minimum value with a y-coordinate of -21. d. the equation has a minimum value with a y-coordinate of -27.

What is the measure of ba (the minor arc) in the diagram below?