Why does vertically falling rain make slanted streaks on the side windows of a moving automobile? If the streaks make an angle of 45°, what does this tell you about the relative speed of the car and the falling rain?

The velocity vectors of rain and car add,making a vector at an angle from the vertical then we can rain steaks on side window.here velocity vectors rain and car are perpendicular to each other. If steaks make an angle 45 .it means the speed of car and rain are same. 0 0 The sum of angle is 180 .the rain and car vectors are two equal sides with a 90 angle between them.the 0 0 0 base angles of isosceles triangle are equal,and these particular two must added up to 90 . 90 /2 = 45 .