1. 1 10-7-14 to 10-9-14 T2.3c We will learn to Solve Double Triangles Please get a handout from the table by the door.

2. 2 Everyone should have a handout with the Starter Activity and examples: Using the information given on the diagram, find the missing angles for the indicated letters. *WORK TOGETHER* 51° 129° 51° 67°

3. 3 Active Learning Questions?

4. 4 Ex: The angle of elevation from the bottom of the Christmas tree to the top is 55°. If I move 28 feet back, the angle of elevation is 20°, how tall is the tree? 55° 20° 28 ft x h LESSON: (You will solve double triangle problems) (1 dec. pl.) -Solve for each triangle -Solve each one for “h” -Use the Substitution Prop. -Use the Distributive Prop. -Subtract “x · tan20” from both sides. +

5. 5 Ex: The angle of elevation from the bottom of the Christmas tree to the top is 55°. If I move 28 feet back and the angle of elevation is 20°, how tall is the tree? 55° 20° 28 ft x h The Christmas tree is 13.7 ft tall. Don’t forget parentheses! (1 dec. pl.) -Factor out common “x” -Divide both sides by (tan55 – tan 20) -Substitute “x” in to find “h” +

6. 6 Try: Franc needs to know the height of a palm tree. From a point on the beach, the angle of elevation to the top of the tree is 36°. He moves 50 feet back and sights another angle of elevation at 22°. How tall is the tree? (1 dec. pl.) First, draw it: Now, solve it. The palm tree is 45.5 ft tall. 36 ° 22° 50’ h x Don’t forget parentheses! +

7. 7 Activity (everyone must be actively involved to earn points) As a group, you will: 1.Discuss and write down what you found most difficult about this lesson and why. Is there anything that I could have done to make it easier? 2.Come up with a situation in which a double triangle solution would be needed. Describe an object to be measured (why?) and the obstacle that is preventing you from measuring the distance to the first angle. 3.Solve it. Your group will turn in one sheet with all your names on it. This will be for a grade. You may have ten minutes to do this, then start on your assignment.

8. 8 Active Learning Assignment (Answers): H/O 3: #13 (114 ft.), #14 (147 m.), #16 (2.5km.) We will have a test on Bearing I, Bearing II, and Double triangles on Wednesday, October 15 th.