solving system of equations produce complex numbers 2

mrahikka shared this problem 7 months ago
Not a Problem

2nd try

Why does this system of equations give complex roots for solution?

b7962b074c90221207dab8370f07a9cc

Comments (5)

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maybe because of the entry mode (use of cos and sin)

try u = cos(a), v = sin(a)

and linearise cos(2a) and sin(2a) before using ratkaise


but it's better to solve with just a pen because this is just two lines

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This seems OK:

Solve({(-3sin(a) + y = (-3a + x) cos(a)),TrigExpand((-cos(2a) + y = -2 (-a + x) sin(2a)))},{x,y})

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Also simplifying the answer is fine:

Simplify(Solve({(-3sin(a) + y = (-3a + x) cos(a)),(-cos(2a) + y = -2 (-a + x) sin(2a))},{x,y}))


Sorry, there's no other improvement we can make with this

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I can undertand that this can very easily be solved without a computer. My question was why. Does this mean that if I have equations with constansts cos(2a), sin(2a) and a, there is a possibility that I get complex roots?

Thanks Mike telling about the Simplify and trigexpand

M

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Does this mean that if I have equations with constansts cos(2a), sin(2a) and a, there is a possibility that I get complex roots?


Sorry, yes

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