# maths (trigonometry)

how can we calculwte the value of
Cot 70 degree+4 cos 70 degree

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3. 👁 551
1. just find
5cos 70°

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2. oops, read the first as cos

I would just use my calculator

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2. 👎 0
3. L.H.S= cos 70/sin 70+4 cos 70
= cos 70+4 cos 70 sin 70/sin 70
=cos 70+2 sin 40/sin 70
= cos 70+2 cos 50/sin 70
= cos 70+cos 50+cos 50/sin 70
= 2 cos 60 cos 10+cos 50/sin 70
= cos 10+cos 50/sin 70
= 2 cos 30 cos 20 /cos 20
= root 3

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2. 👎 1

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