Side c

In △ABC a=2, b=4 and ∠C=100°.

Calculate length of the side c.

Result

c =  4.77

Solution:

c2=a2+b2−2abcos⁡100∘ c=22+42−2⋅2⋅4⋅cos⁡100∘=4.77c^2 = a^2+b^2-2ab \cos 100 ^\circ \ \\ c = \sqrt{ 2^2 + 4^2- 2\cdot 2\cdot 4 \cdot \cos 100 ^\circ } = 4.77

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