cipher's question thread

[cipherpol]

Alright, let's start.

Solve for x algebraically

,

[TrueTears]

This question requires a bit of ingenuity.





Remind you of any compound angle formulas?


You could have squared both sides and simplify etc, but I like wishful thinking more.

[moekamo]

square both sides:



so since

therefore:

or

you can do the rest

[cipherpol]

T.T, I tried squaring both sides and ended up with , which gave the wrong solutions.

[TrueTears]

square both sides:



so since

therefore:

or

you can do the rest

There is only one problem with squaring, it produces redundant solutions. Which is why avoid it if you can, try other ways.

SO DON'T FORGET TO SUB IN VALUES AT THE END TO CHECK VALIDITY!!!

[cipherpol]

Thanks TT, worked perfectly

Next question;

for b.) would I use a formula like ?

[TrueTears]

[cipherpol]

xD, reason I kept getting that last question wrong was cause I was subbing in values from previous answer :uglystupid2:

Last question before moving onto complex numbers!

[TrueTears]

Let be radius of circle.

[cipherpol]

For the next question, so far:





How do I prove they're collinear?

Thanks.

[TrueTears]

I think it's

[cipherpol]

Don't you multiply by the conjugate of ?

[TrueTears]

It's 1 over the conjugate of z

[cipherpol]

omfg, can't believe i didn't see that.

[cipherpol]

Differentiate

Answer says , but I dunno how to get the 6 on top.