Solving Quadratic Trig Equations (Day 1 of 2)

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SWBAT use their knowledge of quadratic equations to solve quadratic trig equations.

Big Idea

The class works together to review methods of solving quadratic equations and make connections to quadratic trig equations.


5 minutes

I begin today's class by asking students to solve the equation on slide 2 of  the flipchart - Solving Quadratic Trig Equations. My goal is to get students thinking about how to solve quadratic equations using inverse operations. I am prepared to remind students that:

  • They should review having to square root both sides of the equation to solve for x (MP7).
  • A quadratic equation can allow 2, 1 or 0 solutions (MP6, MP7). 

If possible I will avoid providing assistance to students on this warm-up problem. I want to assess who can and who cannot solve the problem independently. However, I plan to go over the problem with the class. 

Connecting to Prior Knowledge

40 minutes

In the middle part of today's lesson, my goal is to have students review solving quadratic equations before we move onto solving quadrtaic trigonometric equations in tomorrow's lesson. After guiding students through part 1 of the Student Activity: Solving Quadratic Trig Equations, I will have students work through exercise 1-5 in part II focusing only on the Algebraic form. then students will present their solutions. Here is more detail on how this went my first year teaching it: Solving Quadratic Trig Equations Day 1, Video Narrative, Quadratic Trig Equations


While students are working through this activity the following mathematical practice standards will be addressed:  MP1MP2, MP3MP5MP6, MP7MP8.



10 minutes

To close out today’s lesson, I will ask my students to identify questions they still have about solving quadratic trigonometric equations. First, I will have students write down one question they still have (page 4 in Flipchart). Then, I will encourage students to discuss questions in their teams (page 5 in Flipchart). If questions go unanswered, I will step in and make clarifying suggestions. I want to mak sure that students arrive in a confident place before the end of class (page 6 in Flipchart).