Which pair of expressions below are equivalent?

In a right triangle, we haev some trigonometric relationships between the sides and angles. Given an angle, the ratio between the opposite side to the angle by the hypotenuse is the sine of this angle, therefore, the following statement

$\sin (\theta)=\frac{3}{5}$

Describes the following triangle

To find the missing length x, we could use the Pythagorean Theorem. The sum of the squares of the legs is equal to the square of the hypotenuse. From this, we have the following equation

$x^2+3^2=5^2$

Solving for x, we have

$\begin{gathered} x^2+3^2=5^2 \\ x^2+9=25 \\ x^2=25-9 \\ x^2=16 \\ x=\sqrt[]{16} \\ x=4 \end{gathered}$

The missing length of the first triangle is equal to 4.

For the other triangle, instead of a sine we have a tangent relation. Given an angle in a right triangle, its tanget is equal to the ratio between the opposite side and adjacent side.The following expression

$\tan (y)=\frac{12}{5}$

Describes the following triangle

Using the Pythagorean Theorem again, we have

$5^2+12^2=h^2$

Solving for h, we have

$\begin{gathered} 5^2+12^2=h^2 \\ 25+144=h^2 \\ 169=h^2 \\ h=\sqrt[]{169} \\ h=13 \end{gathered}$

The missing side measure is equal to 13.

Now that we have all sides of both triangles, we can construct any trigonometric relation for those angles.

The sine is the ratio between the opposite side and the hypotenuse, and the cosine is the ratio between the adjacent side and the hypotenuse, therefore, we have the following relations for our angles

$\begin{gathered} \sin (\theta)=\frac{3}{5} \\ \cos (\theta)=\frac{4}{5} \\ \sin (y)=\frac{12}{13} \\ \cos (y)=\frac{5}{13} \end{gathered}$

To calculate the sine and cosine of the sum

$\begin{gathered} \sin (\theta+y) \\ \cos (\theta+y) \end{gathered}$

We can use the following identities

$\begin{gathered} \sin (A+B)=\sin A\cos B+\cos A\sin B \\ \cos (A+B)=\cos A\cos B-\sin A\sin B \end{gathered}$

Using those identities in our problem, we're going to have

$\begin{gathered} \sin (\theta+y)=\sin \theta\cos y+\cos \theta\sin y=\frac{3}{5}\cdot\frac{5}{13}+\frac{4}{5}\cdot\frac{12}{13}=\frac{63}{65} \\ \cos (\theta+y)=\cos \theta\cos y-\sin \theta\sin y=\frac{4}{5}\cdot\frac{5}{13}-\frac{3}{5}\cdot\frac{12}{13}=-\frac{16}{65} \end{gathered}$

4 0

1 year ago

If Florist B increases the cost per rose to $5.20,for what number of roses is it less expensive to order from Florist A? From Fl

Alenkinab [10]

Answer:

For 38 roses at $5.15 per rose, Florist A is Less Expensive then Florist B

For 34 roses at $5.20 per rose, Florist A is Less Expensive then Florist B

Step-by-step explanation:

The Full Question Reads:

Derek wants to order some roses online. Florist A charges $4.75 per blue rose plus $40 delivery charge. Florist B charges $5.15 per red rose plus $25 delivery charge. If Florist B increases the cost per rose to $5.20, for what number of roses is it less expensive to order from Florist A? From Florist B?

To begin we need to understand our given information and what we are actually looking for.

Given Information

Florist A:

charges $4.75 per blue rose

charges $40 per delivery

Florist B:

charges $5.15 per red rose

charges $25 per delivery

Note: in this problem we ignore the colour of the rose (red or blue) as it does not affect our solution or contributes to it. Therefore we shall call our first variable representing the number of roses as $x$ .

The next step is to construct a system of equations representing our problem and our given information. Here we are looking at linear relationships so a linear function of the form:

$y=ax+b$ Eqn(1).

will suffice where

$y$ : represents the total cost from the Florists (i.e. number of roses and delivery charges). Dependent Variable

$x$ : represents the number of roses purchased from the Florists. Independent Variable

$a$ : is our relationship factor between $y$ and $x$

$b$ : is our constant which in this problem is the delivery charge value for each florist.

Since we have two Florists, we will construct two equations, one for each florist, by employing Eqn(1). and our given information as follow:

Florist A: $y=4.75x+40$ Eqn(2).

Florist B: $y=5.15x+25$ Eqn(3).

By employing both equations above and writing them as an inequality since we are looking for which value of $x$ (i.e. number of roses) will the less expensive Florist be and then solving for $x$ we have:

$4.75x+40$

$4.75x-5.15x$ Gathering all similar terms together

$-0.4x$ Simplifying

$x>\frac{-15}{-0.4}\\$ Solving for x

$x>37.5$

(note how < changes to > since any multiplication/devision process of negative sign in an Inequality will change the order of < to > and vice versa).

Since a rose has to be sold as a whole and not half we will say that $x>38$ So we can then plug in the value of $x$ in Eqn(2) and Eqn(3) and find the cost of buying more than 38 roses from each:

Eqn(2): Florist A: $y(x>38)=4.75*38+40=220.5$

Eqn(3): Florist B: $y(x>38)=5.15*38+25=220.7$

Which tells us that Florist A is less expensive than Florist B by $0.20 for a purchase of more than 38 roses.

Next the question tells us that Florist B increases the cost from $5.15 to $5.20 per rose, which in Eqn(3) denotes our $a$ value and thus Eqn(3). now becomes:

Florist B: $y=5.20x+25$ Eqn(3).

Applying the same method like before and solving for the value of $x$ we have:

$4.75x+40$

$4.75x-5.20x$ Gathering all similar terms together

$-0.45x$ Simplifying

$x>\frac{-15}{-0.45}\\$ Solving for x

$x>33.3$

Similarly as a rose has to be sold as a whole and not half we will say that $x>34$ So we can then plug in the value of $x$ in Eqn(2) and Eqn(3) and find the cost of buying more than 34 roses from each:

Eqn(2): Florist A: $y(x>34)=4.75*34+40=201.5$

Eqn(3): Florist B: $y(x>34)=5.15*34+25=201.8$

Which tells us that Florist A is again less expensive than Florist B by $0.30 for a purchase of more than 34 roses. It was also shown that as the cost of the rose increased by $0.05 the number of roses for purchase decreased.

4 0

3 years ago