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? asked in Science & MathematicsMathematics · 6 years ago

Need help with polar form equations!?

Let a= cos(2pi(2/7)) + isin(2pi(2/7))

b= cos(2pi(3/7)) + isin(2pi(3/7))

Find a+b and a-b

Any help would be greatly appreciated!

1 Answer

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  • ted s
    Lv 7
    6 years ago

    hints : sin x + sin y = 2 sin ( [ x + y ] / 2) cos ( [ x - y ] / 2 ).............

    and cos x + cos y = 2 cos ( [ x + y ] / 2 ) cos ( [ x - y ] / 2 )................

    so check the different formulas you can get from combinations of sin (a ±b) and cos (a±b)

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