7.5. Indirect Measurement http://www.ck12.org
- FindOE.
- FindEA.
- Janet wants to measure the height of her apartment building. She places a pocket mirror on the ground 20 ft
from the building and steps backwards until she can see the top of the build in the mirror. She is 18 in from
the mirror and her eyes are 5 ft 3 in above the ground. The angle formed by her line of sight and the ground
is congruent to the angle formed by the reflection of the building and the ground. You may wish to draw a
diagram to illustrate this problem. How tall is the building? - Sebastian is curious to know how tall the announcer’s box is on his school’s football field. On a sunny day he
measures the shadow of the box to be 45 ft and his own shadow is 9 ft. Sebastian is 5 ft 10 in tall. Find the
height of the box. - Juanita wonders how tall the mast of a ship she spots in the harbor is. The deck of the ship is the same height
as the pier on which she is standing. The shadow of the mast is on the pier and she measures it to be 18 ft
long. Juanita is 5 ft 4 in tall and her shadow is 4 ft long. How tall is the ship’s mast? - Evan is 6 ft tall and casts a 15 ft shadow. A the same time of day, a nearby building casts a 30 ft shadow. How
tall is the building? - Priya and Meera are standing next to each other. Priya casts a 10 ft shadow and Meera casts an 8 ft shadow.
Who is taller? How do you know? - Billy is 5 ft 9 inches tall and Bobby is 6 ft tall. Bobby’s shadow is 13 feet long. How long is Billy’s shadow?
- Sally and her little brother are walking to school. Sally is 4 ft tall and has a shadow that is 3 ft long. Her little
brother’s shadow is 2 ft long. How tall is her little brother? - Ray is outside playing basketball. He is 5 ft tall and at this time of day is casting a 12 ft shadow. The basketball
hoop is 10 ft tall. How long is the basketball hoop’s shadow? - Jack is standing next to a very tall tree and wonders just how tall it is. He knows that he is 6 ft tall and at this
moment his shadow is 8 ft long. He measures the shadow of the tree and finds it is 90 ft. How tall is the tree? - Jason, who is 4 ft 9 inches tall is casting a 6 ft shadow. A nearby building is casting a 42 ft shadow. How tall
is the building? - Alexandra, who is 5 ft 8 in tall is casting a 12 ft shadow. A nearby lamppost is casting a 20 ft shadow. How
tall is the lamppost? - Use shadows or a mirror to measure the height of an object in your yard or on the school grounds. Draw a
picture to illustrate your method.