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Math Help - Find the vlue of 4(cos A + cos B + cos C) if...?

  1. #1
    Super Member fardeen_gen's Avatar
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    Find the vlue of 4(cos A + cos B + cos C) if...?

    In a triangle ABC, if 3R = 4r, value of 4(cos A + cos B + cos C) is? (R and r in the triangle have usual notations)

    Ans: 7

    How? I couldn't get 7.
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  2. #2
    Moo
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    Quote Originally Posted by fardeen_gen View Post
    In a triangle ABC, if 3R = 4r, value of 4(cos A + cos B + cos C) is? (R and r in the triangle have usual notations)

    Ans: 7

    How? I couldn't get 7.
    Please explain what R and r are... Because your usual notations are not necessarily everybody's usual notations...
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  3. #3
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    Hello, moo!

    Traditionally, these are the accepted definitions . . .

    . . R is the circumradius, the radius of the circumscribing circle.

    . . r is the inradius, the radius of the inscribed circle.

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