Explain why the graph of the equation g(x) = -(x + 1 ) - 3 would be a parabola opening downward.

Because the a-value is negative.

Step-by-step explanation:

The vertex form of a quadratic equation is: y = a(x - h)² + k    where

Given: g(x) = - (x + 1)² - 3

                    ↓

                 a= -1

Since the a-value is negative, the parabola will be reflected over the x-axis which will change the curve from (U-shaped) to (∩-shaped).

m∠a is 90°

m∠b is 40°