How do you solve $c^2=12^2+10^2-2(12)(10)cos40$ ?

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Answer 1 · 2018-04-08T05:40:57

$color(brown)(c = 7.76$

$c^2 = 12^2 + 10^2 - 2 * 12 * 10 * cos 40$

$c^2 = 144 + 100 - 240 cos 40$

$c^2 = 244 - 240 cos 40$

$c^2 = 244 - 183.85 = 60.15$

$c = +- sqrt(60.15) = +- 7.76$

As c cannot be negative,

$color(brown)(c = 7.76$

How do you solve c^2=12^2+10^2-2(12)(10)cos40c^2=12^2+10^2-2(12)(10)cos40?