Matematika

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cos 150° + sin 45° + 1/2 cot (-330°) = .....

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  • cos 150° + sin 45° + 1/2 cot (-330°) = .....

    cos150°= -cos30=- 1/2 √3
    sin 45° = 1/2 √2
    cot (-330°) =-cot330°= cot 30°= √3

    =- 1/2 √3 + 1/2 √2 + 1/2 × √3
    =- 1/2 √3 + 1/2 √2 + 1/2√3
    = 1/2 √2

  • cos 150° + sin 45° + 1/2 cot (-330°)
    = cos (180° - 30°) + sin 45° - 1/2 cot 330°
    = - cos 30° + sin 45° - 1/2 cot (270° + 60°)
    = - cos 30° + sin 45° - 1/2 (- tan 60°)
    = - 1/2 √3 + 1/2 √2 + 1/2 √3
    = 1/2 √2

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