RonnyDeKoning 3 years ago tan (- alpha) and - tan alpha, what is the different between those 2 "-"'s

1. hartnn

no difference, both are negatives.

2. RonnyDeKoning

But, I don't understand this:tan (-alpha) = -tan alpha

3. hartnn

if alpha is in 1st quadrant - alpha is in 4th quadrant. In 4th quadrant, tan ratio is negative. hence, tan(-x)=-tan x

4. RonnyDeKoning

I don't understand.

5. hartnn

what exactly is your doubt ?

6. RonnyDeKoning

so (tan (-x) is from the 4th quadrant and -tan x in the first, how can it be negative in the first.

7. hartnn

a ratio can't be in any quadrant.... x is an angle, its in 1st quadrant., then tan x is positive. if x is in 1st quadrant, -x is in 4th quadrant, where tan x is negative, so, we need to bring out -*minus* sign and write tan(-x) = - tan x (....and NOT tan(-x)=tan x)

8. RonnyDeKoning

What is a ratio?

9. hartnn

sin,cos , tan,.... are ratios...

10. RonnyDeKoning

I a making an ex: and see this: tan x = -1 <=> - tan x (pi/4) Why is the - before tan?

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