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Mathss help pleaseeee

Hii! I need help with this! How come the answer i wrote isnt the answer?

help mee.PNG
The inverse tan of -0.6745 is -34 degrees

And the tan function is periodic every 180 degrees
Original post by whitedwarf
The inverse tan of -0.6745 is -34 degrees

And the tan function is periodic every 180 degrees

Im sorryy.. i still dont understand. It's a new topic and because of quantifier, my teacher hasn't taught us any of this

doesnt wrok.PNG
Original post by actinglover
Hii! I need help with this! How come the answer i wrote isnt the answer?

help mee.PNG


maybe a comma instead of “and”
Original post by zacn01
maybe a comma instead of “and”

Noppe that didnt work :frown:
Original post by actinglover
Noppe that didnt work :frown:


I got 146 and 326 from arctan(-0.6745), adding 180 to it.
Original post by zacn01
I got 146 and 326 from arctan(-0.6745), adding 180 to it.

I lost all my marks when i put that in:frown:
Original post by actinglover
Im sorryy.. i still dont understand. It's a new topic and because of quantifier, my teacher hasn't taught us any of this

doesnt wrok.PNG

oh okay :biggrin: ill try to explain

this is what the tan graph looks like


y = tan(x)

and the question is asking to find the x value (degrees) at which the y value is equal to -0.6745

in order to find x, you do the inverse tan of y. this gives you -34 degrees

the question asks for answers between 0 and 360 degrees
and from the graph, you can see that the function is periodic every 180 degrees so if you add 180 to -34, you end up with the same y value
and if you add another 180 to that, you end up with the same y value

therefore, -0.6745 = tan(-34) = tan(146) = tan(326) = tan(506) etc
Original post by whitedwarf
oh okay :biggrin: ill try to explain

this is what the tan graph looks like


y = tan(x)

and the question is asking to find the x value (degrees) at which the y value is equal to -0.6745

in order to find x, you do the inverse tan of y. this gives you -34 degrees

the question asks for answers between 0 and 360 degrees
and from the graph, you can see that the function is periodic every 180 degrees so if you add 180 to -34, you end up with the same y value
and if you add another 180 to that, you end up with the same y value

therefore, -0.6745 = tan(-34) = tan(146) = tan(326) = tan(506) etc

Omg thank you for the explanation. i could tell it took kind of long to write it out. Its so weird tho because when i put 139, i gain 2 marks and i need one more mark

huh..PNG
see?
Original post by actinglover
Omg thank you for the explanation. i could tell it took kind of long to write it out. Its so weird tho because when i put 139, i gain 2 marks and i need one more mark

huh..PNG
see?

no problem

do you need to press the little plus button in the answer box to add another answer maybe?
Original post by actinglover
Omg thank you for the explanation. i could tell it took kind of long to write it out. Its so weird tho because when i put 139, i gain 2 marks and i need one more mark

huh..PNG
see?

139 is not correct but 146 and 326 is
Original post by Muttley79
139 is not correct but 146 and 326 is

it's a different question to above
Original post by whitedwarf
it's a different question to above

So find the other angle using the method you were shown.
tan is negative when x lies on quadrant II or IV, i.e. 90 <x<180 or 270<x<360.
tan is negative when x lies on quadrant II or IV, i.e. 90 <x<180 or 270<x<360.

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