## Ask Singapore Homework?

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Hope it helps

Date Posted:
2 weeks ago

ahh, ok i get it, thank you so much !!

tan 5x = tan 2x

tan 5x - tan 2x = 0

Then we divide both sides by (1 + tan 5x tan 2x). Since tan 5x = tan 2x, the value of tan 5x tan 2x will be at least zero, so we won’t run into zero denominator issues.

The left-hand side will look very much like the tangent addition formula!

tan (5x - 2x) = 0

tan 3x = 0

And you can follow the tutor’s workings afterwards.

Sine, cosine and tangent are actually length ratio operators in triangles and should not be treated as algebraic.

In particular, we cannot, for example, say that sin (A + B) = sin A + sin B, in contrast with expressions such as k (A + B) = kA + kB.

When you learnt sine, for example, it was defined as the trigonometric ratio of the length of an opposite side to the hypotenuse side of a triangle with respect to a particular angle chosen.

Most people would have forgotten about this “ratio” word in trigonometry and some people would then accordingly make the error of “expanding” or “factorising” such expressions.

Logarithmic expressions are also similar; they are another type of operator altogether and in a similar way, log (A + B) is not equivalent to log A + log B in general.