If the altitudes of a triangle meet at one of the triangles vertices then the triangle is what type of triangle and why?

Which statements are true? see picture

How many solutions does the nonlinear system of equations graphed below have?

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters