By first differentiating (√(1-x))/(√(1+x)) obtain an expression dy/dx in terms of x. hence show that the gradient of the normal to the curve at point (x, y) is (1+x)(√(1-x^2))

Mr. brettler is hanging up a 5-foot tall rectangular welcome sign in the gym. he has drawn a sketch on a coordinate grid. he has the lower vertices of the sign at (9, –3) and (–6, –3). where would the upper vertices be on the grid?