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If cosalpha+cosbeta=0=sinalpha+sinbeta. ...

If `cosalpha+cosbeta=0=sinalpha+sinbeta`. Prove that `cos2alpha+cos2beta=-2cos(alpha+beta)`

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If cosalpha+cosbeta=0=sinalpha+sinbeta, then prove that cos2alpha+cos2beta=-2cos(alpha+beta) .

If cosalpha+cosbeta=0=sinalpha+sinbeta , then prove that cos2alpha +cos2beta=-2cos(alpha +beta) .

Knowledge Check

  • If cosalpha+cosbeta=0=sinalpha+sinbeta , then cos2alpha+cos2beta=?

    A
    `-2sin(alpha+beta)`
    B
    `2cos(alpha+beta)`
    C
    `2sin(alpha+beta)`
    D
    `-2cos(alpha+beta)`

  • If cos alpha+cos beta=0=sin alpha+sinbeta, then cos2alpha+cos 2beta=

    A
    `-2sin(alpha+beta)`
    B
    `-2cos (alpha+beta)`
    C
    `2sin(alpha+beta)`
    D
    `2cos (alpha+beta)`

  • If cosalpha+cosbeta=0=sinalpha+sinbeta,cos2alpha+cos2beta is equal to a) -2sin(alpha+beta) b) 2cos(alpha+beta) c) 2sin(alpha-beta) d) -2cos(alpha+beta)

    A
    `-2sin(alpha+beta)`
    B
    `2cos(alpha+beta)`
    C
    `2sin(alpha-beta)`
    D
    `-2cos(alpha+beta)

    • Similar Questions

    Explore conceptually related problems

    If cosalpha+cosbeta=0=sinalpha+sinbeta , then prove that cos2alpha +cos2beta=-2cos(alpha +beta) .

    If cosalpha+cosbeta=0=sinalpha+sinbeta , then prove that cos2alpha+cos2beta+2cos(alpha+beta)=0

    If cosalpha+cosbeta=0=s inalpha+s inbeta, then prove that cos2alpha+cos2beta=-2cos(alpha+beta)dot

    If cosalpha+cosbeta=0=sinalpha+sinbeta" then "cos2alpha+cos2beta

    If cosalpha+cosbeta=0=sinalpha+sinbeta, then cos2alpha+cos2beta is equal to (a) -2"sin"(alpha+beta) (b) -2cos(alpha+beta) (c) 2"sin"(alpha+beta) (d) 2"cos"(alpha+beta)

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