X + 9 = 18 + -2X X = 5 X-3 X-7

We are given with an angle of depression of the bird to the field mouse of 50 degrees while the distance from the base tree to the mouse of 40 meters. To get the height of the bird from the ground, we take the tan of 50. We express tan 50 = height / base distance. tan 50 = height/ 40 meters. Hence the height is 47.7 meters.