Answer:
d) 135º
Step-by-step explanation:
Note that the angle DCU is the sum of the angles DCB and BCU. The angle DCB is 90º because A B C D is a square, then all its angles are equal to 90º.
After attaching B U C to A B C D, we obtain a trapezoid A U C D. Since A U C D has at least one pair of parallel sides, then AU should be parallel to CD, thus the angle CBU must be 90º.
B U C is isoceles, so we conclude that other two angles must have the same size, and due to the sum of the angles of a triangle being 180º, then both BUC and BCU are equal to 45º
As a result, the angle DCU is equal to 90º+45º = 135º. Option d is the correct one.
22 gallons is 83.279 liters
Answer:
The actual mass of the book is between 481 . 5 g and 418 . 5 g.
Step-by-step explanation:
The mass of the book on the scale = 450 g
The percentage error in the scale = 7%
So, the actual mass of the book is 450 g ± 7%
Now, 7 % of the mass 450 g = 
⇒ 7% of 450 g = 31.5 g
Now, the Actual mass of the book = 450 g ± 31.5 g
450 g + 31.5 g = 481 . 5 g
450 g - 31.5 g = 418 . 5 g
Hence the actual mass of the book is between 481 . 5 g and 418 . 5 g.