## Algebra and Trigonometry 10th Edition

$\theta = 104.48^{o}$ $\phi = 75.52$ c = 63.24
The following are the given values: a = 40 b = 60 d = 80 Using the Law of Cosines, we can find $\theta$: $cos(\theta) = \frac{40^{2} + 60^{2} - 80^{2}}{2(40)(60)}$ $\theta = 104.48^{o}$ Knowing that a parallelogram has $360^{o}$, we can find $\phi$: $\frac{360 - (104.48)(2)}{2} = 75.52$ $\phi = 75.52$ Using the Law of Cosines, we can find c: $c^{2} = 40^{2} + 60^{2} - 2(40)(60)cos(75.52^{o})$ c = 63.24 $\theta = 104.48^{o}$ $\phi = 75.52$ c = 63.24