What is the reference angle for the angle with measure −π4 ?

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

The length of a rectangle is x times the square root of 100. the width is one-half y more than three-halves x. given that the area of the rectangle is 125 cm2, which equation could represent the rectangle in terms of x and y? a) 5xy − 15x = 125 b) 5xy + 15x = 125 c) 15x2 − 5xy = 125 d) 15x2 + 5xy = 125

What are the solutions of the equation? 6x^2 + 11x + 4 = 0 a. 4/3, 1/2 b. -4/3, -1/2 c. 4/3, -1/2 d. -4/3, 1/2