• 1. r = √8²+10²-2*8*10*cos60
    r = √64+100-80
    r = √84
    r = 2√21 cm

    2. sin 600 + sec 660 - cot 690
    = sin (360+240) + sec (360+300) - cot (360+330)
    = sin 240 + sec 300 - cot 330
    = sin (180+60) + sec (360-60) - cot (360-30)
    = -sin60 + sec 60 + cot 30
    = -0.5√3 + 2 +√3
    = 2+0.5√3

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