4.2

 After studying this section, you will be able to:  organize the information and  draw diagrams for problems presented in words.

 “ If two altitudes of a triangle are congruent, then the triangle is isosceles.”  1. Draw the shape, label everything.  2. The “if” part of the statement is the “given.”  3. The “then” part of the statement is the “prove.”  4. Write the givens and what you want to prove.

1.Draw a diagram to show two altitudes in a triangle. 1.Label everything. 2. Write your given statements. 3. Write your prove statement. Given: BD & CE are altitudes to AC & AD of ACD. BD = CE. Prove: ACD is isosceles. A C BE D

 “The medians of a triangle are congruent if the triangle is equilateral.”  1. Draw the diagram.  2. Write down the givens you need.  3. What do you need to prove?

1.Draw a diagram to show the medians in an equilateral triangle. 2. Label everything! 3. Write your given statements. 4. Write your prove statement. Given: XYZ is equilateral. PZ, RY, and QX are medians. Prove: PZ= RY=QX X PR YZ Q

 Set up a proof of this statement: The opposite angles of a parallelogram are congruent. HINT  The sentence begins with the given information and ends with the conclusion.

Given: ABCD is a parallelogram Prove: B D C A

 Go to your designated station. You will meet your partner there.  Set up the proof: Draw and label the diagram Write the “Given” and the “Prove” DO NOT SOLVE!!! You will have less than five minutes at each station

 p. 178 #5, 7, 9, 10