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Week 17 in Pre-Calc 11

This week, we have learned trigonometry and I will discuss one of the things I learned: the Sine Law.


It’s a very useful to solve any triangle as long as you have:

  • an angle that has a side corresponding it.
  • two angles / two sides / one angle and one side.

Here’s how it works: every angle needs to be written in CAPITAL LETTERS and every side needs to be written in LOWER CASE LETTERS.

angle A corresponds with side a or side BC.

angle B corresponds with side b or side AC.

angle C corresponds with side c or side AB.


what’s the formula?

if you’re finding an angle…

\frac{sinA}{a} = \frac{sinB}{b} = \frac{sinC}{c}


and if you’re finding a side…

\frac{a}{sinA} = \frac{b}{sinB} = \frac{c}{sinC}


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