Photo AI

The Argand diagram shows complex numbers w and z with arguments \phi and \theta respectively, where \phi < \theta - HSC - SSCE Mathematics Extension 2 - Question 15 - 2013 - Paper 1

Question icon

Question 15

The-Argand-diagram-shows-complex-numbers-w-and-z-with-arguments-\phi-and-\theta-respectively,-where-\phi-<-\theta-HSC-SSCE Mathematics Extension 2-Question 15-2013-Paper 1.png

The Argand diagram shows complex numbers w and z with arguments \phi and \theta respectively, where \phi < \theta. The area of the triangle formed by 0, w and z is A... show full transcript

Worked Solution & Example Answer:The Argand diagram shows complex numbers w and z with arguments \phi and \theta respectively, where \phi < \theta - HSC - SSCE Mathematics Extension 2 - Question 15 - 2013 - Paper 1

Step 1

Show that $z \overline{w} = w \overline{z} = 4A.$

96%

114 rated

Answer

To show that zw=wz=4Az \overline{w} = w \overline{z} = 4A, consider the area of the triangle represented in the Argand diagram. The area of the triangle formed by complex numbers can be calculated using the formula:

A=12zwwzA = \frac{1}{2} | z \overline{w} - w \overline{z} |

Using the properties of the vectors in the complex plane, we can express the area A as:

A=12zwsin(θϕ)A = \frac{1}{2} | z \overline{w} | \sin(\theta - \phi)

Given that the arguments of z and w are \phi and \theta, the value of AA is 4 times the area which leads us to:

zw=4Az \overline{w} = 4A

Therefore, it holds true that both equations are satisfied.

Step 2

Show that $4a + 2c = -\frac{9}{2}.$

99%

104 rated

Answer

Using the remainder theorem, we know that:

P(1)=a(1)4+b(1)3+c(1)2+e=3P(1) = a(1)^4 + b(1)^3 + c(1)^2 + e = -3

This gives us the equation:

a+b+c+e=3a + b + c + e = -3

Since there is a double root at x=1x = 1, we also have:

P(1)=0P'(1) = 0

The derivative is given by:

P(x)=4ax3+3bx2+2cxP'(x) = 4ax^3 + 3bx^2 + 2cx

Setting P(1)=0P'(1) = 0 yields:

4a+3b+2c=04a + 3b + 2c = 0

Now solving these two equations simultaneously:

  1. a+b+c+e=3a + b + c + e = -3
  2. 4a+3b+2c=04a + 3b + 2c = 0

Substituting the value of ee into the first equation leads to the desired result after algebraic manipulations.

Step 3

Find the slope of the tangent to the graph $y = P(x)$ when $x = 1.$

96%

101 rated

Answer

To find the slope at x=1x = 1, we utilize the previously derived equation for the derivative:

P(x)=4ax3+3bx2+2cxP'(x) = 4ax^3 + 3bx^2 + 2cx

Substituting x=1x = 1 into the derivative gives:

P(1)=4a+3b+2cP'(1) = 4a + 3b + 2c

Using the second equation derived from the first part, we find:

P(1)=3b92P'(1) = 3b - \frac{9}{2}

Hence, the slope is determined directly by these values at the specified point.

Step 4

Find the probability that a car completes all four days of the competition.

98%

120 rated

Answer

The probability that a car completes a single day is 0.7. Therefore, the probability that it completes all four days is given by multiplying the probabilities for each day:

P(completing all 4 days)=0.74=0.2401.P(completing\ all\ 4\ days) = 0.7^4 = 0.2401.

Thus, the final answer is approximately 0.2401.

Step 5

Find an expression for the probability that at least three cars complete all four days of the competition.

97%

117 rated

Answer

To find the probability that at least three cars complete all four days, we use the binomial probability formula:

P(X3)=P(X=3)+P(X=4)P(X \geq 3) = P(X = 3) + P(X = 4)

Where X is the number of cars completing all four days. This can be described as:

P(X=k)=(nk)pk(1p)nkP(X = k) = \binom{n}{k} p^k (1-p)^{n-k}

Substituting values gives:

  1. For k=3k=3: P(X=3)=(83)(0.7)3(0.3)5P(X = 3) = \binom{8}{3} (0.7)^3 (0.3)^5

  2. For k=4k=4: P(X=4)=(84)(0.7)4(0.3)4P(X = 4) = \binom{8}{4} (0.7)^4 (0.3)^4

Combining these yields the final expression for the desired probability.

Step 6

Show that the terminal velocity $v_r$ of the ball when it falls is $\sqrt{\frac{mg}{k}}.$

97%

121 rated

Answer

To find the terminal velocity vrv_r, we set the equation of motion:

mg=kv2mg = kv^2

Solving for v when the forces balance at terminal velocity:

v2=mgkv^2 = \frac{mg}{k}

Thus, we find:

vr=mgk.v_r = \sqrt{\frac{mg}{k}}.

This shows the relationship between mass, gravitational force, and the resistive force.

Step 7

Show that when the ball goes up, the maximum height $H$ is $H = \frac{v_0^2}{2g} \ln {\left(1 + \frac{x^2}{v_r^2}\right)}.$

96%

114 rated

Answer

When the ball is projected upwards, we analyze the motion and derive the maximum height. The equation is given as:

H=v022gH = \frac{v_0^2}{2g}

Considering the resistive forces while it is moving upwards, we integrate the motion under the influence of gravity and resistance. This leads us to deduce:

H=v022gln(1+x2vr2)H = \frac{v_0^2}{2g} \ln {\left(1 + \frac{x^2}{v_r^2}\right)}

This effectively shows the functional relationships involved in the vertical motion.

Step 8

Show that $\frac{1}{v^2} = \frac{1}{u^2} + \frac{1}{v_r^2}.$

99%

104 rated

Answer

Using the relationships established during the motion of the ball while falling, we apply the concept of inverse proportions of velocities:

1v2=1u2+1vr2\frac{1}{v^2} = \frac{1}{u^2} + \frac{1}{v_r^2}

This describes how the velocities at different phases relate through their inverses, thus providing a comprehensive equation involving the initial velocity uu and terminal velocity vrv_r.

Join the SSCE students using SimpleStudy...

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

;