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January 26, 2015

January 26, 2015

Posted by **ashley --** on Tuesday, April 26, 2011 at 2:07pm.

- trig -
**MathMate**, Tuesday, April 26, 2011 at 2:28pmThe longest diagonal forms a triangle with 180°-40°=140° and adjacent sides of 42 and 36 cm.

Using the cosine rule:

C²=A²+B²-2ABcos(α)

=42²+36²-2*42*36*cos(140°)

=1764+1296-3024(-.766044443)

=5376.52 approx.

C=sqrt(5376.52)

=73.32 cm (approx.)

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