1. Measuring Angles

Find the measure of each marked angle. In Exercises 19–22, m and n are parallel. See Examples 1 and 2 .

In each figure, there are two similar triangles. Find the unknown measurement. Give anyapproximation to the nearest tenth.

The measures of two angles of a triangle are given. Find the measure of the third angle. See Example 2. 37° , 52°

Length of a Shadow If a tree 20 ft tall casts a shadow 8 ft long, how long would the shadow of a 30-ft tree be at the same time and place?

The measures of two angles of a triangle are given. Find the measure of the third angle. See Example 2. 147° 12' , 30° 19'

The measures of two angles of a triangle are given. Find the measure of the third angle. See Example 2. 29.6° , 49.7°

The measures of two angles of a triangle are given. Find the measure of the third angle. See Example 2. 17° 41' 13" , 96° 12' 10"

Concept Check Classify each triangle as acute, right, or obtuse. Also classify each as equilateral, isosceles, or scalene. See the discussion following Example 2.

Concept Check Classify each triangle as acute, right, or obtuse. Also classify each as equilateral, isosceles, or scalene. See the discussion following Example 2.

Convert each radian measure to degrees. See Examples 2(a) and 2(b). ―7π/20

Convert each radian measure to degrees. See Examples 2(a) and 2(b). 11π/30

Concept Check Classify each triangle as acute, right, or obtuse. Also classify each as equilateral, isosceles, or scalene. See the discussion following Example 2.

Convert each radian measure to degrees. See Examples 2(a) and 2(b). 15π

Find the unknown side lengths in each pair of similar triangles. See Example 4.

Solve each problem. See Example 5. Height of a Lighthouse The Biloxi lighthouse in the figure casts a shadow 28 m long at 7 A.M. At the same time, the shadow of the lighthouse keeper, who is 1.75 m tall, is 3.5 m long. How tall is the lighthouse?