Lesson 5

Access hints as you need them to complete this activity.

1. Study “Example 4” on page 299 of the textbook. Note the two ways to solve the equation.
   
   
2. Solve “Your Turn” at the bottom of page 299. It may be helpful to make your own drawing of the bottom of the box and the side view.
   
   

Self-Check 1

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1. The power in watts (W) of an electric appliance is equal to the current in amps (A) squared multiplied by the resistance in ohms (Ω).
   
   
   1. Express the statement above as an equation, where power is P, current is I, and resistance is R. Answer
      
      
   2. Rearrange the equation to isolate current, I. Answer
      
      
   3. How much current flows through a 1600-W hair dryer that has a resistance of 8.82 Ω? Answer
      
2. Most new television screens have a 16:9 aspect ratio. This means the width is  times the height. When a television is advertised as having a 42-in screen, it means the length of the diagonal of the screen is 42 in.
   
   
   1. What is the height of a 42-in screen? Begin by letting the height be h. Then express the width in terms of the height. Make a drawing using your variables and putting in the length of the diagonal. Use the Pythagorean theorem to set up an equation and solve for the height. Is your answer reasonable? Answer
      
      

   2. What is the width of a 42-in screen? How can you check your answer? Answer
      
      

   3. What is the total viewing area of a 42-in screen? Answer

Skip forward to Connect if you feel you have a solid understanding of how to

• solve a problem that involves radical expressions
  
  
• solve problems by modelling situations using radical equations
  

If you need a bit more practice, complete Self-Check 2.

Self-Check 2

Complete any or all of questions 14, 15, 16, and 17 on pages 301 and 302 of the textbook. As you finish each part of a question, check your work against the answers given at the back of the textbook. If you are still unclear about how to answer some questions, ask your teacher about those questions and get some help.