Trigonometric Proofs (2 Viewers)

[Lukybear]

prove:

 

[jet]

 

[Lukybear]

thanks!!

 

[Aquawhite]

What a disgusting mess

I absolutely loathe trigonometry! >.<

 

[ianc]

edit: whoops wrong thread sorry

 

[Lukybear]

One more: I got partial answer... Just want to see working out

Thanks

Solve


Also:

 

[jet]

 

[Lukybear]

wow much thanks!!

But question about second ones.

I solved only for tanx which caused me to go wrong. In which cases does both trig identifies have to be solved?

 

[jet]

wow much thanks!!

But question about second ones.

I solved only for tanx which caused me to go wrong. In which cases does both trig identifies have to be solved?

Always always always.
The basic rule is NEVER eliminate one of the functions, because this could eliminate solutions.
e.g sinxcosx = cosx. You dont go sinx = 1 by dividing by cos x.
You would go sinxcosx-cosx = 0 and go from there.

 

[Lukybear]

o wow, thanks. Teacher never taugh us that.

Also for the first question, in the end you mentioned that tan270 is undefined therefore it is not answer. What is the general rule for this?

 

[jet]

I'm not sure what you mean. it is just a known fact that tan270° is undefined.

tan270° = sin270/cos270
= -1/0
= Undefined as you cannot divide by zero.
You cannot calculate the value of tan for any multiple of 90°

 

[gurmies]

Always always always.
The basic rule is NEVER eliminate one of the functions, because this could eliminate solutions.
e.g sinxcosx = cosx. You dont go sinx = 1 by dividing by cos x.
You would go sinxcosx-cosx = 0 and go from there.

Very true. By dividing by cosx, you're assuming it can't be zero. If you choose to use this method, always check at the end whether angles like pi/2, 3pi/2 were solutions.

 

[Gibbatron]

Trigonometric proofs are the absolute pits. Worse that parabola proofs, which are shocking enough.

 

[Drongoski]

Trigonometric proofs are the absolute pits. Worse that parabola proofs, which are shocking enough.

I'm really surprised. Proving trigonometric identities at MX1 level is relatively trivial, I'd have thought.

 

[MaNiElla]

thats right

 

[Gibbatron]

I'm really surprised. Proving trigonometric identities at MX1 level is relatively trivial, I'd have thought.

it may be trivial but i think its extremely tedious and annoying.

 

[Lukybear]

I need help again...

Ladder X is clined to wall at angle a. Foot is fixed. If ladder was y cm longer, inclination to the horizontal would be B. Show the distance from the foot of the ladder to the wall is given by

Prove:



is the bottom horizontal distance

And alrite Dron... We know your smart...

 

[Aerath]

 

[Lukybear]

Aerath, cant see pic... where attach it to your thread?

 

[Aerath]

Here we go.