When I'm working out a maths or physics problem I always find myself questioning whether I should work out the equation as I go along or should I re arrange it and do it in one step with my calculator?(adsbygoogle = window.adsbygoogle || []).push({});

For example if I was to use the cosine rule for triangles,

a^{2}=b^{2}+c^{2}-2bccosA

to solve a triangle for angle A with sides a, b and c as 20, 30 and 40 respectively.

Is this better written out as,

a^{2}=b^{2}+c^{2}-2bccosA

20^{2}=30^{2}+40^{2}-2*30*40*cosA

400=900+1600-2400cosA

-2100=-2400cosA

7/8=cosA

A=cos^{-1}(7/8)

A=29.0°(1D.P.)

or

a^{2}=b^{2}+c^{2}-2bccosA

A=cos^{-1}[itex]\left(\frac{b^{2}+c^{2}-a^{2}}{2bc}\right)[/itex]

A=cos^{-1}[itex]\left(\frac{30^{2}+40^{2}-20^{2}}{2*30*40}\right)[/itex]

A=cos^{-1}(7/8)

A=29.0(1D.P.)

Thanks

AL

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# Best way to write formulae or equations ?

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