Question

Trigonometric Equation

2tan^2A + 3secA = 0

Answer 1

@hartnn
Another one please

Answer 2

which pythagorean identities do you know ?

Answer 3

I've bee through all except for the half identities

Answer 4

@hartnn

Answer 5

so which identity relates tan^2 A and sec^2 A ?

Answer 6

Sin?

Answer 7

I mean cos?

Answer 8

ever sen this ?
\(\\tan^2 A =sec^2A-1\)
?
use it here

Answer 9

Yes. I'm familiar with that

Wait. Let me try

Answer 10

I got 2x^2+3x-2
Is it right?
So i may move on

Answer 11

yes,
that = 0
remember its an equation, not an expression

Answer 12

Oh right

Answer 13

How'll this be nothing will equal to 3x?

Answer 14

@hartnn ^

Answer 15

what ? i didn't get your question...

Answer 16

2x^2+3x-2 = 0

x= .....
x=....

Answer 17

Oh sorry

What i meant was what should i do next?
How do i find x?
I cant use the FOIL method.

Answer 18

factor method.

2 numbers with sum = +3 and product = -4

Answer 19

Got it

Wait

Answer 20

Sec = 1/2
Sec={no solution

Sec=-2
No solution

?????
I dont know
Hpw's this?
@hartnn

Answer 21

sec A can be -2

Answer 22

I dont see any negative 2 in the graph list

Sec A =-2

Answer 23

sec A = -2

secA = 1/cos A

cos A = -1/2
when ?

Answer 24

I dont see any cos A =-1/2
There is only cos A=1/2

Answer 25

Or did i get it wrong?

Answer 26

@hartnn ^

Answer 27

how about angles 120 and 210 ?

Answer 28

Where did you get that.
Those arent in the graph that was given to us

Answer 29

http://en.wikipedia.org/wiki/File:Unit_circle_angles_color.svg

Answer 30

Oh i see now

So will the answer for secA=-2 or cosA=-1/2 be:

A={120,210}

Answer 31

Is that it already?

How about sec=1/2? Does it really have no solution?

@hartnn

Answer 32

yes. in the range 0 to 360.

range of sec function does not include values between -1 and 1
so, sec A = 1/2 will have no solution,
(in the same way cos A = 2 have no solution)

Answer 33

Okay thanks again

Answer 34

welcome ^_^