# Trigonometry

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• Jan 6th 2008, 02:39 PM
sadaf_rehman
Trigonometry
Two sides of a paralellogram measure 7.0cm and 9.0cm. THe longer diagonal is 12 cm long. Calculate all the interior angles , to the nearest degree, of the paralellogram.
• Jan 6th 2008, 03:20 PM
Henderson
Do you know the Law of Cosines?

$c^2 = a^2 + b^2 - 2ab\cos(\theta)$, so
$12^2 = 7^2 + 9^2 - 2(7)(9)cos(\theta)$.

Solve that for $\theta$, and you have one angle, and its opposite. The other two angles are supplements of that angle ( $180 - \theta$).