Answer:
w = 6
Step-by-step explanation:
5w-26 = - 4 (w - 7) multiply -4 through
5w - 26 = - 4w + 28 add 4w to each side to cancel it out on the right
5w + 4w - 26 = 28
9w - 26 = 28 Now add 26 to each side
9w - 26 + 26 = 28 + 26
9w = 54 Now divide each side by 9
(9w)/9 = 54/9
w = 6
Answer:
A theorem stating that the square of the length of the hypotenuse of a right triangle is equal to the sum of the squares of the lengths of the other sides. It is mathematically stated as c2 = a2 + b2, where c is the length of the hypotenuse and a and b the lengths of the other two sides.
Step-by-step explanation:
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.