Original post by zyiad
can I have tan x in terms of tan 2x ?
If yes
write it
If yes
write it
Take the identity for tan(2x) in terms of tan(x), reareange it into a quadratic for tan(x), solve it.
Original post by RDKGames
Take the identity for tan(2x) in terms of tan(x), reareange it into a quadratic for tan(x), solve it.
I could not
can you do it for me plz
Original post by the bear
T = 2t/{ 1- t2 }
make t the subject
*T = tan2x
t = tanx
make t the subject
*T = tan2x
t = tanx
how?
Original post by zyiad
how?
rearrange it to get a quadratic equation with t as the variable, as RDK suggested above.
Original post by zyiad
how?
Original post by the bear
rearrange it to get a quadratic equation with t as the variable, as RDK suggested above.
I could not rearrange themcan you help me?
Original post by zyiad
I could not rearrange themcan you help me?
T = 2t/{ 1- t2 }
T{ 1 - t2 } = 2t
T - t2T = 2t
- t2T = 2t - T
t2T =- 2t +T
t2T + 2t - T =0
now use the quadratic formula with a = T, b = 2, c = -T
Original post by the bear
T = 2t/{ 1- t2 }
T{ 1 - t2 } = 2t
T - t2T = 2t
- t2T = 2t - T
t2T =- 2t +T
t2T + 2t - T =0
now use the quadratic formula with a = T, b = 2, c = -T
T{ 1 - t2 } = 2t
T - t2T = 2t
- t2T = 2t - T
t2T =- 2t +T
t2T + 2t - T =0
now use the quadratic formula with a = T, b = 2, c = -T
Thank you
Original post by the bear
T = 2t/{ 1- t2 }
T{ 1 - t2 } = 2t
T - t2T = 2t
- t2T = 2t - T
t2T =- 2t +T
t2T + 2t - T =0
now use the quadratic formula with a = T, b = 2, c = -T
T{ 1 - t2 } = 2t
T - t2T = 2t
- t2T = 2t - T
t2T =- 2t +T
t2T + 2t - T =0
now use the quadratic formula with a = T, b = 2, c = -T
There are two solutions to the equation.
Can I exclude one of the solutions?
Original post by zyiad
There are two solutions to the equation.
Can I exclude one of the solutions?
Can I exclude one of the solutions?
yes... for instance if T = tan 60°
tan 30° = t
===> tan230° + 2tan30° - tan60° = 0
this must only give a single, positive, value for tan30° so we can discard the negative answer.
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