From the setup of the problem, the "length of the top of the bookcase, measured along the attic ceiling" will be the hypotenuse of a right triangle, the length "AB". We have both the angle between AB and AC and the length of AC (3.24 meters), so we can use trigonometric identities.
The cosine of the 40 degree angle between AB and AC is equivalent to the length of AC divided by the length of AB. Equivalently, we have:

where "h", the hypotenuse, is the length we want. Rearranging the formula to solve for h we have that

which is 4.2295... meters. Converting to centimeters (multiplying by 100) we have that h = 422.95... centimeters, or if we round the value, h = 423 centimeters.
Answer:
54 cups of flour
Step-by-step explanation:
Answer:
3
Step-by-step explanation:
It means absolute value 7 plus -4
This means that if it were a -7, it would become positive because it is under absolute value bars...since it is positive nothing changes
7-4= 3
Answer:
63 eggs.
Step-by-step explanation:
7 times 3 equals 21, which is the amount of eggs one chicken lays in 9 days. Multiply that by 3, you get 63.