Answer:
A ≈ 3420 cm²
Step-by-step explanation:
The area (A) of a circle is calculated as
A = πr² ( r is the radius ) , then
A = π × 33² = 1089π ≈ 3420 cm² ( to 3 significant figures )
Answer: Choice D)
The angle between the two vectors is approximately 71.6 degrees
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Work Shown:
Each time I write the word "dot" I mean "dot product".
|u| = length of vector u
|u| = sqrt(u dot u)
|u| = sqrt(<8,4> dot <8,4>)
|u| = sqrt(8*8 + 4*4)
|u| = sqrt(64 + 16)
|u| = sqrt(80)
|u| = sqrt(16*5)
|u| = sqrt(16)*sqrt(5)
|u| = 4*sqrt(5)
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|v| = length of vector v
|v| = sqrt(v dot v)
|v| = sqrt(<9,-9> dot <9,-9>)
|v| = sqrt(9*9 + (-9)*(-9))
|v| = sqrt(81+81)
|v| = sqrt(2*81)
|v| = sqrt(2)*sqrt(81)
|v| = sqrt(2)*9
|v| = 9*sqrt(2)
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u dot v = <8,4> dot <9,-9>
u dot v = 8*9 + 4*(-9)
u dot v = 72-36
u dot v = 36
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cos(theta) = (u dot v)/(|u|*|v|)
cos(theta) = (36)/(4*sqrt(5)*9*sqrt(2))
cos(theta) = (36)/(36*sqrt(10))
cos(theta) = 1/(sqrt(10))
cos(theta) = sqrt(10)/10
theta = arccos(sqrt(10)/10)
theta = 71.56505
which rounds to 71.6 when rounding to one decimal place (nearest tenth)
That's why the approximate answer is roughly 71.6 degrees
Answer:
Step-by-step explanation:
Let he speed of the boat on the lake is x.
<u>Considering the speed of the current it will take him:</u>
- 22.5/(x + 6) + 22.5/(x - 6) = 9
- 2.5 / (x + 6) + 2.5 / (x - 6) = 1
- 2.5(x - 6 + x + 6) = (x + 6)(x - 6)
- 2.5*2x = x² - 36
- x² - 5x - 36 = 0
- x = (5 ± √(5² + 4*36))/2 = (5 ± 13) / 2
- x = (5 + 13)/2 = 9 mph (negative root is discarded as the speed should be positive)
Answer:
the answer is C
Step-by-step explanation:
40,000/.80 = 50,000
50,000 x .10 = 5,000
50,000 - 5,000 = 45,000
45,000 x .06 =2700
45,000 + 2,700 = 47,700
