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# trig watch

1. ive done the first part of this question and found that the roots of an equation are

-1+/- rt2

one of these is tan 22.5 (-1+rt2)

then the next part says to express the other root in trigometric form and i dont get it!!

thanks
2. (Original post by sarah12345)
ive done the first part of this question and found that the roots of an equation are

-1+/- rt2

one of these is tan 22.5 (-1+rt2)

then the next part says to express the other root in trigometric form and i dont get it!!

thanks
let a = -1 + rt2, b = - 1 - rt2, @ = 22.5

Note ab = -1 by difference of squares and a = [email protected]

so b = -1/[email protected] = cot([email protected]) = tan(pi/[email protected])

how do they want it in trig form? there are lots of ways of writing it?

probably would help if you wrote out the whole question
3. the question is write out the formula for tan 2x. deduce that tan 22.5 is a root of the equation t^2+2t-1+0 and hence find the exact value of tan 22.5
express the other root of the quadratic in trigometrical form
4. (Original post by sarah12345)
the question is write out the formula for tan 2x. deduce that tan 22.5 is a root of the equation t^2+2t-1+0 and hence find the exact value of tan 22.5
express the other root of the quadratic in trigometrical form
Well they could be asking for [email protected] or tan(pi/[email protected]) I guess either is right as they're not specific

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