Chapter 8 - Application of Trigonometry - Summary Exercises on Applications of Trigonometry and Vectors - Exercises - Page 791: 1

$29\ ft, 38\ ft$

1. Label the given figure as shown, we have angle $\angle ADB=90^\circ-20^\circ=70^\circ$ 2. Use the Law of Cosines, we have $x=\sqrt {15^2+30^2-2(15)(30)cos70^\circ}\approx29\ ft$ 3. We have angle $\angle ADC=180^\circ-70^\circ=110^\circ$ 4. Use the Law of Cosines, we have $y=\sqrt {15^2+30^2-2(15)(30)cos110^\circ}\approx38\ ft$