Two lines are perpendicular if they lie on the same plane and cross at angles. (FILL IN THE BLANK)

90 degree

Step-by-step explanation:

right angles is the answer

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value

1 number

if we use a graphing calculator, there is only one such number that satisfies the conclusion of the mean value theorem, that is, a number such that

where the right-hand side is the average rate of change of f on the interval [0.5,0.75], which is the slope of the secant line.

in the attached graph, the black line is the secant line which has its slope as the average rate of change of f on [0.5,0.75], while the orange line is the only tangent line to the graph of f in the interval that satisfies the mvt conclusion.