Express the complex number in trigonometric form.
1 answer:
-5i can be written as 0 + (-5)i
It is in the form a+bi where a = 0 and b =-5
So the point (a,b) is (0,-5)
The distance from the origin to this point is 5 units, therefore r = 5. This is the magnitude.
The angle is 270 degrees as shown in the attached image. You start on the positive x axis and rotate until you reach the point (0,-5)
This is why the answer is choice A) 5(cos(270) + i*sin(270))
It is in the form a+bi where a = 0 and b =-5
So the point (a,b) is (0,-5)
The distance from the origin to this point is 5 units, therefore r = 5. This is the magnitude.
The angle is 270 degrees as shown in the attached image. You start on the positive x axis and rotate until you reach the point (0,-5)
This is why the answer is choice A) 5(cos(270) + i*sin(270))
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Option B
Circumference of a circle is C = 2πr.
part 1)
so the radius of the smaller gear is 3 inches, so after a full rotation, namely a revolution, the smaller gear has covered an arc of 2π(3), or 6π.
what angle has the larger gear of 7 inches in radius, has it covered with an arc of 6π?
part 2)
since the larger gear has a radius of 7, in a revolution it will have an arc of 2π(7), or 14π.
now, we know the smaller gear does a 6π arc in a revolution, how many revolutions will it do in an arc of 14π?
part 1)
so the radius of the smaller gear is 3 inches, so after a full rotation, namely a revolution, the smaller gear has covered an arc of 2π(3), or 6π.
what angle has the larger gear of 7 inches in radius, has it covered with an arc of 6π?
part 2)
since the larger gear has a radius of 7, in a revolution it will have an arc of 2π(7), or 14π.
now, we know the smaller gear does a 6π arc in a revolution, how many revolutions will it do in an arc of 14π?
Suppose you add x liters of pure water to the 10 L of 25% acid solution. The new solution's volume is x + 10 L. Each L of pure water contributes no acid, while the starting solution contains 2.5 L of acid. So in the new solution, you end up with a concentration of (2.5 L)/(x + 10 L), and you want this concentration to be 10%. So we have
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