The three angles of a triangle are (x-25) degrees, (2x+40)degrees and 30 degrees. find the magnitude of each angle.

2 answers

This an easy deal when recalling the fundamental identity for traingles, namely that the sum of the three angles must be identically 180 degrees. (Why precisely 180°?)
This means:

(x-25) + (2x+40) + 30 = 180

This can be simplified to:

3x + 45 = 180

Subtracting 45 on both sides yields:

3x = 135

Multiplying this 1/3-times, one immediately finds:

x=45

It is not neceassry but quite useful to substitute the obtained value directly back into the aforementioned equation in order to verify this as the solution.

Question to think further: Why is there just one solution?
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