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C2 trig help

upthegunners

Solve:

Okay so I draw my quadrant diagram like this:

thanks

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Reply 1

Hopple

Go round again. cos (stuff) = cos (stuff+360)

Reply 2

FizzicsGuy

add 360 to each of your 2 solutions until the answers exceed the boundaries.

Reply 3

upthegunners

Original post by GreigM

add 360 to each of your 2 solutions until the answers exceed the boundaries.

Is this the case for cos, sine or tangent?

I always get confused about this

Reply 4

FizzicsGuy

Original post by upthegunners

Is this the case for cos, sine or tangent?

I always get confused about this

it is the same for all of them.

Reply 5

upthegunners

Original post by GreigM

it is the same for all of them.

I heard that you add 180deg to the tan function as it's period is 180?

Reply 6

FizzicsGuy

Original post by upthegunners

I heard that you add 180deg to the tan function as it's period is 180?

You're probably right. I haven't learned for tan yet as I'm with the Scottish education system

I will post my working to it underneath.

Reply 7

FizzicsGuy

ImageUploadedByStudent Room1365946488.920469.jpg

Am I right because if not I need to do all of this again 😞

Posted from TSR Mobile

Reply 8

TenOfThem

Original post by upthegunners

I heard that you add 180deg to the tan function as it's period is 180?

In the example that you showed you had the 2 solutions less than 360

If you had both of them for Tan then the rule of adding 360 to both answers still applies

Reply 9

TenOfThem

Original post by GreigM

Am I right because if not I need to do all of this again

You are correct

We do not advise posting complete solutions

I understand that you wanted to check your own understanding but it would be better to hide your solution using a

Spoiler

(edited 11 years ago)

Reply 10

upthegunners

Original post by TenOfThem

In the example that you showed you had the 2 solutions less than 360

If you had both of them for Tan then the rule of adding 360 to both answers still applies

So in what situations do we not add 360?

Reply 11

TenOfThem

Original post by upthegunners

So in what situations do we not add 360?

I do not really understand your question

If you have a solution you can always add 360 to get another solution

Reply 12

Mr M

Study Forum Helper

Original post by upthegunners

Is this the case for cos, sine or tangent?

I always get confused about this

The period of the tan graph is 180 degrees.

The period of the sin and cos graphs is 360 degrees.

Reply 13

upthegunners

Original post by Mr M

The period of the tan graph is 180 degrees.

The period of the sin and cos graphs is 360 degrees.

so to get another solution for a tan function we add 180 and NOT 360?

Reply 14

Mr M

Study Forum Helper

Original post by upthegunners

so to get another solution for a tan function we add 180 and NOT 360?

360 will get you another answer but you will obviously miss one out!

Reply 15

.raiden.

Original post by upthegunners

so to get another solution for a tan function we add 180 and NOT 360?

Adding 180 twice is the same as adding 360 :s-smilie:

Reply 16

upthegunners

Original post by TenOfThem

I do not really understand your question

If you have a solution you can always add 360 to get another solution

from the that persons solutions I can see they DO NOT add 360/2pi degrees

If I add 2pi to pi/6 I get 13pi/6 not 5pi/5

what am I doing wrong? :frown:

thanks

Reply 17

.raiden.

Original post by upthegunners

from the that persons solutions I can see they DO NOT add 360/2pi degrees

If I add 2pi to pi/6 I get 13pi/6 not 5pi/5

what am I doing wrong? :frown:

thanks

The limit states that x is not greater than 2pi

Reply 18

TenOfThem

Original post by upthegunners

from the that persons solutions I can see they DO NOT add 360/2pi degrees

If I add 2pi to pi/6 I get 13pi/6 not 5pi/5

what am I doing wrong? :frown:

thanks

Why are you adding 2pi to pi/6

arc cos 1/2 = pi/3