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3 years ago

Adnan states if cos30°≈0.866, then sin30°≈0.866.

Mathematics

1 answer:

kiruha [24]3 years ago

8 0

Answer:

Adnan is incorrect because cosx and sin(90 - x) are always equivalent in any right triangle ⇒ first answer

Step-by-step explanation:

In any right triangle there are two acute angles sum of them is 90°

∴ If one of them x°, then the other is (90 - x)°

∵ cos x = adjacent/hypotenuse

∵ sin(90 - x) = opposite/hypotenuse

∵ The opposite of ∠(90 - x) is the adjacent of ∠x

∴ cosx = sin(90 - x)

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Find the maximum and minimum values of the function f(x,y)=2x2+3y2−4x−5 on the domain x2+y2≤100. The maximum value of f(x,y) is:

ryzh [129]

First find the critical points of f :

$f(x,y)=2x^2+3y^2-4x-5=2(x-1)^2+3y^2-7$

$\dfrac{\partial f}{\partial x}=2(x-1)=0\implies x=1$

$\dfrac{\partial f}{\partial y}=6y=0\implies y=0$

so the point (1, 0) is the only critical point, at which we have

$f(1,0)=-7$

Next check for critical points along the boundary, which can be found by converting to polar coordinates:

$f(x,y)=f(10\cos t,10\sin t)=g(t)=295-40\cos t-100\cos^2t$

Find the critical points of g :

$\dfrac{\mathrm dg}{\mathrm dt}=40\sin t+200\sin t\cos t=40\sin t(1+5\cos t)=0$

$\implies\sin t=0\text{ OR }1+5\cos t=0$

$\implies t=n\pi\text{ OR }t=\cos^{-1}\left(-\dfrac15\right)+2n\pi\text{ OR }t=-\cos^{-1}\left(-\dfrac15\right)+2n\pi$

where n is any integer. We get 4 critical points in the interval [0, 2π) at

$t=0\implies f(10,0)=155$

$t=\cos^{-1}\left(-\dfrac15\right)\implies f(-2,4\sqrt6)=299$

$t=\pi\implies f(-10,0)=235$

$t=2\pi-\cos^{-1}\left(-\dfrac15\right)\implies f(-2,-4\sqrt6)=299$

So f has a minimum of -7 and a maximum of 299.

4 0

3 years ago

One of the parking lot lights at a hospital has a motion detector on it, and the equation (x+10)2+(y−8)2=16 describes the bounda

Pani-rosa [81]

We are given an equation:
$(x+10)^{2} + (y-8)^{2} = 16$

This is an equation of a circle. General form of a circle equation is:
$(x-a)^{2} + (y-b)^{2} = r^{2}$
Where:
a = x coordinate of a center
b = y coordinate of a center
r = radius of a circle

Motion detector can detect person anywhere within a boundary. The greatest distance at which detector can detect is at the edge of a circle. That distance, between detector and edge of circle, is equal to radius.

From the equation we have:
$r^{2} =16 \\ r=4$
The greatest distance at which person can be detected is 4ft.

7 0

3 years ago

Read 2 more answers

Help very fast please help me

Irina18 [472]

Find the discount price and subtract from the total to find the sale price.

To find the discount price, multiply 90 b 40% (convert 40% into decimal)

90 x 0.4 = 36

Next, subtract the discount from the total to find the sale price.

90 - 36 = 54

So, the sale price is $54.

6 0