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.
You go it right it's the first one
$315, i cant give a thorough explanation since i did it all in my head but basically amal gets 5 portions of the money and Salma gets 9, meaning she gets 4 more, so if 4 portions is $252 then it cant be any of the others since they are too low or way too high, $315 is the only reasonable one.
Answer:
( -1, 1 )
Step-by-step explanation:
For f ( x ) = tan x ; Range = R (real no.)
Range in interval = ( -1, 1 )