A fountain on a lake sprays water in a parabolic arch modeled by the equation y = -0.3x2 + 3x. A beam of light modeled by the equation -2x + 5.5y = 19.5 passes through the fountain to create a rainbow effect. If the beam cuts the water spray at points A and B, such that point B is at a higher level than point A, what distance from the ground level is point A?
Water model ⇒⇒⇒ y = -0.3 x² + 3x ( blue graph ) Light model ⇒⇒⇒ -2x + 5.5 y = 19.5 ( red graph ) The intersection between the two models A and B A = ( 1.657 , 4.148 ) B = ( 7.13 , 6.138 )
B is at a higher level than point A
The distance from the ground level to point A = y-coordinate of point A = 4.148
