# Lesson 9

Drawing Triangles (Part 1)

Let’s see how many different triangles we can draw with certain measurements.

### Problem 1

Use a protractor to try to draw each triangle. Which of these three triangles is impossible to draw?

1. A triangle where one angle measures $$20^\circ$$ and another angle measures $$45^\circ$$
2. A triangle where one angle measures $$120^\circ$$ and another angle measures $$50^\circ$$
3. A triangle where one angle measures $$90^\circ$$ and another angle measures $$100^\circ$$

### Problem 2

A triangle has an angle measuring $$90^\circ$$, an angle measuring $$20^\circ$$, and a side that is 6 units long. The 6-unit side is in between the $$90^\circ$$ and $$20^\circ$$ angles.

1. Sketch this triangle and label your sketch with the given measures.
2. How many unique triangles can you draw like this?

### Problem 3

1. Find a value for $$x$$ that makes $$\text-x$$ less than $$2x$$.
2. Find a value for $$x$$ that makes $$\text-x$$ greater than $$2x$$.
(From Unit 5, Lesson 13.)

### Problem 4

One of the particles in atoms is called an electron. It has a charge of -1. Another particle in atoms is a proton. It has charge of +1.

The overall charge of an atom is the sum of the charges of the electrons and the protons. Here is a list of common elements.

charge from
electrons
charge from
protons
overall
charge
carbon -6 +6 0
aluminum -10 +13
phosphide -18 +15
iodide -54 +53
tin -50 +50

Find the overall charge for the rest of the atoms on the list.

(From Unit 5, Lesson 3.)

### Problem 5

A factory produces 3 bottles of sparkling water for every 7 bottles of plain water. If those are the only two products they produce, what percentage of their production is sparkling water? What percentage is plain?

(From Unit 4, Lesson 3.)