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4 years ago

(15-4i)(6-3i) = a +bi

Mathematics

1 answer:

kati45 [8]4 years ago

7 0

The real part of the result is the product of the real parts of the factors and the product of the imaginary parts:

a = 15*6 - (-4)(-3) = 90 -12 = 78

_____

You can treat this the same as any other product of binomials except that i² = -1.

... (15 -4i)(6 -3i) = 15(6 -3i) -4i(6 -3i) = 15·6 -15·3i -4·6i +4·3i²

... = 90 -45i -24i +12i² = (90 -12) -69i = 78 -69i

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A ship sails 250km due North qnd then 150km on a bearing of 075°.1)How far North is the ship now? 2)How far East is the ship now

olga_2 [115]

Answer:

1) 288.8 km due North

2) 144.9 km due East

3) 323.1 km

4) 207°

Step-by-step explanation:

Bearing: The angle (in degrees) measured clockwise from north.

Trigonometric ratios

$\sf \sin(\theta)=\dfrac{O}{H}\quad\cos(\theta)=\dfrac{A}{H}\quad\tan(\theta)=\dfrac{O}{A}$

where:

$\theta$ is the angle
O is the side opposite the angle
A is the side adjacent the angle
H is the hypotenuse (the side opposite the right angle)

Cosine rule

$c^2=a^2+b^2-2ab \cos C$

where a, b and c are the sides and C is the angle opposite side c

-----------------------------------------------------------------------------------------------

Draw a diagram using the given information (see attached).

Create a right triangle (blue on attached diagram).

This right triangle can be used to calculate the additional vertical and horizontal distance the ship sailed after sailing north for 250 km.

Question 1

To find how far North the ship is now, find the measure of the short leg of the right triangle (labelled y on the attached diagram):

$\implies \sf \cos(75^{\circ})=\dfrac{y}{150}$

$\implies \sf y=150\cos(75^{\circ})$

$\implies \sf y=38.92285677$

Then add it to the first portion of the journey:

⇒ 250 + 38.92285677... = 288.8 km

Therefore, the ship is now 288.8 km due North.

Question 2

To find how far East the ship is now, find the measure of the long leg of the right triangle (labelled x on the attached diagram):

$\implies \sf \sin(75^{\circ})=\dfrac{x}{150}$

$\implies \sf x=150\sin(75^{\circ})$

$\implies \sf x=144.8888739$

Therefore, the ship is now 144.9 km due East.

Question 3

To find how far the ship is from its starting point (labelled in red as d on the attached diagram), use the cosine rule:

$\sf \implies d^2=250^2+150^2-2(250)(150) \cos (180-75)$

$\implies \sf d=\sqrt{250^2+150^2-2(250)(150) \cos (180-75)}$

$\implies \sf d=323.1275729$

Therefore, the ship is 323.1 km from its starting point.

Question 4

To find the bearing that the ship is now from its original position, find the angle labelled green on the attached diagram.

Use the answers from part 1 and 2 to find the angle that needs to be added to 180°:

$\implies \sf Bearing=180^{\circ}+\tan^{-1}\left(\dfrac{Total\:Eastern\:distance}{Total\:Northern\:distance}\right)$

$\implies \sf Bearing=180^{\circ}+\tan^{-1}\left(\dfrac{150\sin(75^{\circ})}{250+150\cos(75^{\circ})}\right)$

$\implies \sf Bearing=180^{\circ}+26.64077...^{\circ}$

$\implies \sf Bearing=207^{\circ}$

Therefore, as bearings are usually given as a three-figure bearings, the bearing of the ship from its original position is 207°

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What operation do you use to convert 50 cups to gallons?

zzz [600]

Division can be used. For example

50/16=3.125gallons

or you could use multiplication

50*1/16=3.125gallons

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3 years ago

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Which point is a solution to the inequality shown in this graph?

Hitman42 [59]

Ur answer is (0,-3)

because ur line is a solid line, this means any number on that line is a solution....along with any points that are in the blue area. when u plot ur answer choices, if it falls in the white area, it is not a solution

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3 years ago

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1) Find the volume of the figure below. Round to the tenth place, if

AleksandrR [38]

Answer:

It should be 396

Step-by-step explanation:

11x6=66

66x6 should get u to 396

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3 years ago

Which of these transformations preserves distance and angle measure.

Andreyy89

Answer:Reflections

Step-by-step explanation:

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