Question

This help please #12, 13, and 14 ! Im really stuck and I have a math test soon

Answer 1

bloody hell :D

Answer 2

12 is evil D:

Answer 3

:(

Answer 4

Or not haha

Answer 5

Sorry, mental block a while a go... but it's all good now :D

Answer 6

Use cofunctions. Remember that
\[\Large \cot(\theta) = \tan\left(\frac \pi 2 - \theta\right)\]

Answer 7

oh got it !

Answer 8

thanks :)

Answer 9

I need #13 and also determining the exact value for #14 oh wait 12 b aswell :(

Answer 10

Sorry for my lack of activity... really disoriented right now o.O

Answer 11

For #13 sin x=cos 3pi/11

Express cos in sine.

Answer 12

Then you can simply equate x. Sin(pi/2-x)=cos x

Answer 13

#14 is a simple application of the forms:
sin(A+B),sin(A-B),cos(A+B), cos(A-B)

Answer 14

yeah I got sin ( 5π/ 12 + π/4)

Answer 15

but how do i got exact?

Answer 16

Isn't it 5pi/22 ?

Answer 17

not for 14 a

Answer 18

forr 13 the right answer is 17pi / 22 but I also got 5 pi over 22

Answer 19

Sin x=sin y can have multiple solutions.

The general format is x=npi+((-1)^n)y if I remember right.

Answer 20

For 14 a, simplify the expression you got. You will land on the answer.

Answer 21

oh okay thanks !

Answer 22

Did you get 12 b?

Answer 23

No

Answer 24

It's quite easy. I will give you a hint:

tan 13pi/9=tan(pi+4pi/9)

Answer 25

how do you know when to subtract and add?

Answer 26

#15 as well. Oh my I hate getting stuck on questions.

Answer 27

Okay... I'm back to optimal running conditions.. :D
What'd I miss? ^_^

Answer 28

12 b and 15 :}

Answer 29

15 looks like fun :D

Answer 30

You can either use identities or draw a right-triangle.

It doesn't matter that much, take your pick, whichever you're more comfy with ^_^

Answer 31

Right triangle :)

Answer 32

Okay.
Let's draw that damn right triangle (in the first quadrant, since the question specifies it so)

Answer 33

So this is the angle x.
Catch me so far?

Answer 34

yes !

Answer 35

Sine is opposite over hypotenuse, so since the sine is 4/5, we'll have the opposite side be 4... and the hypotenuse be 5.
Like this.

Answer 36

Alright I have it drawn like that aswell

Answer 37

Okay, can you find the missing side?
Use the Pythagorean theorem.

Answer 38

x^2+4^2=25^2
x^2=625-16
x^2=609

Answer 39

x=25.6 ... this seems so wrong

Answer 40

oh shoot I did 25 -_- wait

Answer 41

the answer is 3 !

Answer 42

so cos x = 3/5 ?

Answer 43

okay I got it ! :)

Answer 44

would I do the same for #16 but instead multiply it be 2 after ?

Answer 45

I'm sorry again... you got cos correct :)

Answer 46

You haven't done 15b yet, though... you do something similar, only you're given cos this time...