# Chapter 11 - Review Exercises: 29

The grade of the hill is 3:7 or 3 to 7.

#### Work Step by Step

1. Find the $\angle B$ in $\triangle ABC$ $\angle B = 180 - (90 + 23)$ (Angles in a triangle add to 180˚) $\angle B = 180 - 113$ $\angle B = 67˚$ $\angle A = 23˚$ (Given) $\angle C = 90˚$ (Given) 2. Use the sine law to find the value of b $\frac{b}{sin67} = \frac{3}{sin23}$ $b = \frac{3sin67}{sin23}$ $b = \frac{2.6715...}{0.39073...}$ $b = \frac{2.6715...}{0.39073...}$ $b = 7.067 ft$ $b \approx7$ ft 3. Take the a and b value to find the grade Grade $= a$ to $b$ Grade $= 3$ ft to $7$ ft

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