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Mathematics 16 Online
Nicole:

http://prntscr.com/nrf7dj

Nicole:

@Narad

Narad:

The domain of \[y=sinx\] is all real numbers \[D _{f} = \mathbb{R} \]

Nicole:

http://prntscr.com/nrfalb

Narad:

Since \[-1\le sinx \le 1\] The range is \[-1 \le y \le1\]

Nicole:

http://prntscr.com/nrfcj3

Narad:

The domain of the function \[y=cosx\] is all real numbers \[D _{f} = \mathbb{R} \]

Nicole:

http://prntscr.com/nrfebc

Narad:

Since the domain of \[y=tanx\] is\[x \in (-\pi/2, \pi/2)\] The range is \[y \in \mathbb{R} \] that is , all real numbers

Nicole:

okay http://prntscr.com/nrffmd

Narad:

When \[x=0\] \[f(0)=\ 0.5tan0=0\] This is not the case in the graph Therefore, The answer is FALSE

Nicole:

Got it http://prntscr.com/nrfisd

Narad:

Since the graph passes through the origin, The first, second and fourth options are not correct \[y= 2tanx\] When \[x=\pi/4\] \[y=2\] from the graph The correct option is option C

Nicole:

Okay http://prntscr.com/nrfko3

Narad:

Since the range is \[-1\le y \le 1\] You can remove option D \[f(x)=2sinx\] Also you can remove \[f(x)=sinx+2\] for the same reasons With respect to the graph of \[f(x)=sinx\] This graph has been shifted to the right by \[\pi/4\] The answer is option A \[f(x)=\sin(x-45)\]

Nicole:

Okay http://prntscr.com/nrfo6x

Narad:

When \[x=0\] \[f(0)=\sin(0-180)-1=\sin(-180)-1=0-1=-1\] This point lies on the curve When \[x=0.5\pi\] \[f(0.5\pi)=\sin(90-180)-1=\sin(-90)-1=-1-1=-2\] This point also lies on the curve when \[x=-0.5\pi\] \[f(-0.5\pi)=\sin(-90-180)-1=\sin(-270)-1=1-1=0\] This point is on the curve We can, therefore, conclude that \[f(x)=\sin(x-180)-1\] is the equation of the graph This is TRUE

Nicole:

Okay http://prntscr.com/nrfsaw

Narad:

When\[x=0\] \[f(0)=\cos0-3=1-3=-2\] This point does not lie on the curve When \[x=\pi/2\] \[f(\pi/2)=\cos(\pi/2)-3=0-3=-3\] This point does not lie on the curve We can conclude that the equation of the graph is not \[f(x)=cosx-3\] The answer is FALSE

Nicole:

okay http://prntscr.com/nrfx32

Narad:

The following points lie on the curve \[(0,0)\] \[(\pi/2,1)\] \[(-\pi/2,-1)\] The domain is \[\mathbb{R} \] and the range is \[-1\le f(x)\le1\] This function is \[f(x)=sinx\] THe answer is option B

Nicole:

Okay http://prntscr.com/nrg2tc

Narad:

The cosine of an angle is by definition \[\cos=\] (adjacent)/(hypotenuse) In the triangle ABC \[cosB=BC/AB=a/c\] You can reject the first three options The correct answer is option D

Nicole:

okay http://prntscr.com/nrg558

Narad:

The tangent of an angle is by definition \[\tan\] =(opposite)/(adjacent) Therefore, in the triangle ABC \[tanA=BC/AC= a/b\] You can reject the first 3 options and accept option D

Nicole:

Got it http://prntscr.com/nrg85a

Narad:

By definition, \[sine\] of an angle is =(opposite)/(hypotenuse) Here, in the triangle ABC \[\sin B=AC/AB=5/13\] You can accept the first option and reject the others

Nicole:

Okay http://prntscr.com/nrg8vy

Narad:

The tangent of an angle is tan=(opposite)/(adjacent) Here in the triangle ABC \[\tan B=AC/BC=9/12=3/4\] The answer is option C

Nicole:

Okay http://prntscr.com/nrgate

Narad:

The secant of an angle is secant = (hypotenuse)/(adjacent) Here, in the triangle ABC \[secA= AB/AC=13/5\] You can accept the first option and reject the others

Nicole:

Okay http://prntscr.com/nrgcby

Narad:

The sine of an angle is by definition sine=(opposite)/(hypotenuse) Therefore, in the triangle ABC \[sinA=BC/AB=12/15=4/5\] You can accept the third option C

Nicole:

Okay http://prntscr.com/nrge3c

Narad:

Question nº19 \[cosA=0.34\] Therefore, \[A = \cos ^{^-1} 0.34\] From my calculator, \[A= 70.12º\] The answer is option B

Narad:

Question nº20 \[sinB=0.45\] Therefore, \ From my calculator, \ The correct answer is option D

Nicole:

Okay http://prntscr.com/nrgftx

Narad:

Something went wrong in the last answer, can you read everything

Nicole:

Maybe its 47?

Narad:

The cosine of an angle is by definition cosine=(adjacent)/(hypotenuse) Therefore, In the triangle ABC cos40º=AC/AB = AC/3 therefore, AC=3*cos40º= 2.30 cm

Narad:

I'll rewrite question nº20 sinB=0.45 B=arcsinB=arcsin(0.45) From my calculator B=0.47 The answer is option D

Nicole:

http://prntscr.com/nrl8fe

Nicole:

@Narad

Narad:

The tangent og an angle is defined as tangent=(opposite)/(adjacent) Apply this to the triangle ABC tanA=BC/AC BC=AC*tanA=29.3*tan28º =15.58 mi

Nicole:

Got it http://prntscr.com/nrlazw

Narad:

Since the triangle is right angled and the sum of the angles of a triangle is =180º B+28º=90º B=90-28=62º

Nicole:

Okay http://prntscr.com/nrlb7k

Narad:

The altitude = height of the plane = 8 mi The distance to the runaway (hypotenuse)= 175 mi The sine of an angle is sine=(opposite)/(hypotenuse) sin(angle)=8/175=0.046 The angle is = 2.62º

Nicole:

http://prntscr.com/nrlc5i

Narad:

Since the triangle is a right angled isoceles triangle (45º,45º,90º) The height above 6feet is=60feet The height of the building is =60+6=66ft

Nicole:

okay http://prntscr.com/nrlfcd

Narad:

We have already done this question f(0)=0 f(pi/2)=1 f(-pi/2)=-1 The equation of the graph is f(x)=sinx The correct option is B

Nicole:

Okay http://prntscr.com/nrlfn3

Narad:

The points are f(pi/4)=0 f(3/4pi)=1 f(-pi/4)=-1 and the range is y = [-1, 1] The equation of the graph is a sine function which has been translated to the right by pi/4 Therefore, f(x)=sin(x-45º) or f(x)=sin(x-pi/4)

Nicole:

http://prntscr.com/nrmdy9

Narad:

The domain of the graph is All Real Numbers The range of the graph is = [-2, 2] = 2* [-1, 1] The values taken by the graph are f(0)=0 f(-pi/2)=-2 f(pi/2)= 2 The equation of the graph is y=2sinx

Nicole:

http://prntscr.com/nrw8xh

Narad:

Question nº29 The range of y=tanx is All Real Numbers Therefore, The range of y=tanx+2 is also All Real Numbers

Narad:

Question nº30 The range of y=sinx is \[-1 \le sinx \le 1\] The range of y=2sinx is \[-2 \le 2sinx \le 2\] The range of y=2sinx +1 is \[-1 \le 2sinx +1 \le 3\] The answer is \[y \in [-1, 3]\]

Nicole:

http://prntscr.com/nrwdxp

Narad:

Question nº31 180º is equivalent to \[\pi\] radians Therefore, 125º is equal to \[\pi/180*125 rad\] \[=25/36\pi\] The answer is the last option, option D

Narad:

Question nº32 \[\pi\] radians is equivalent to 180º Therefore, 3.6 radians is equivalent to \[180/\pi*3.6\] \[= 206.3 º\] The answer is the first option, option A

Nicole:

okay http://prntscr.com/nrwefl

Narad:

Question nº33 180º is equivalent to \[\pi rad\] Therefore, 135º is equivalent to \[\pi/180*135= 3/4\pi\] The answer is \[=3/4\pi\]

Narad:

Question nº34 Let's first convert 150º into radians The conversion is \[150º=\pi/180*150 = 5/6\pi\] Therefore, The cosine of 150º, according to the unit circle is \[\cos150º =-\cos30º =-\sqrt3/2\]

Nicole:

okay http://prntscr.com/nrwi76

Narad:

Question nº 35 The cosine of the angle is \[cosA =-0.45\] This means that the angle is in 2nd Quadrant or 3rd Quadrant Therefore \[A=\cos ^{-1} (-0.45) =2.04rad = 116.74º\] Here the answer is in the 2nd Quadrant

Narad:

Question nº 36 The current is dragging you downstream Therefore, \[\tan 25º = 375/d\] So, \[d=375/\tan25º = 804.2ft\] The distance downstream is = 804.2 ft

Nicole:

Okay http://prntscr.com/nrwn31

Narad:

The domain is \[x \in \mathbb{R} \] The range is \[y \in [-1, 1]\] Particulars values are \[f(0)=0\] \[f(\pi/2)=1\] and \[f(-\pi/2)=-1\] The equation of the graph is \[y=sinx\]

Nicole:

okay http://prntscr.com/nrwvuh

Narad:

The domain is \[ x \in \] The range is \[ y \in [-1, 5]\] Particular values are \[f(0)=2\] \[f(\pi/2)=5\] and \[f(-\pi/2)=-1\] This is a sinusoidal function \[y = 3sinx +2\] The equation of the graph is \[y=3sinx+2\]

Narad:

Domain is \[x \in \mathbb{R} \]

Nicole:

Okay and last one: http://prntscr.com/nrwy5q

Narad:

The range of sinx is \[-1\le sinx \le 1\] so, \[-3 \le 3sinx \le3\] And \[0 \le 3sinx+3 \le 6\] The range of the function\[y = 3sinx+3\] is \[y \in [0, 6]\]

Nicole:

Thank you!

Narad:

You are welcome

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