Lesson Plan Format
Class: Geometry
Date: April 15, 2014
Topic: Right Triangles: Sine, Cosine,
Tangent
Period:
I.
Estimated Time: 50 minutes
Standards:
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CC.2.3.HS.A.3
Verify and apply geometric theorems as they relate to geometric figures.
CC.2.3.HS.A.7
Apply trigonometric ratios to solve problems involving right triangles.
Goal:
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Students will explore how to use Sine, Cosine, and Tangent to solve for missing
information in a right triangle.
II. Objectives:
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Students will use Pythagorean’s Theorem to solve for missing sides of a right triangle.
Students will use the sum of the angles to solve for missing angles of a right triangle.
Students will use Sine, Cosine, and Tangent to solve for missing sides and angles of a
right triangle.
Students will explore the concepts of Sine, Cosine, and Tangent.
III. Materials/Equipment:
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IV.
Do Now worksheet
Exploration worksheet
Calculators
Computer
Closing/Homework worksheet
Blank paper
Protractor
Ruler
Procedures:
A. Engagement Activity/Anticipatory Set:
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Do Now Activity: Students will be given a do now activity which has them use
Pythagorean’s Theorem to find missing sides of right triangles and using the sum
of angles to find missing angles of a right triangle.
After students finish the worksheet they will pair share their answers and select
students will present their answers using the doc cam.
B. Body/Instructional Plan:

Students will be given an exploratory worksheet to learn how they can use Sine,
Cosine, and Tangent to solve for the missing pieces of a right triangle. This
worksheet should be done in partners. Students will then share their findings with
the rest of their table.
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After students finish the worksheet, the whole class will discuss the results found.
The important information that needs to be discussed is the relationships between
the sides of the triangle and the angles when using the trig identities.
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The teacher will then explain SOH CAH TOA to help students understand these
concepts.
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There will also be a discussion on why these ratios hold true using similar
triangles.
C. Closure and Extending Activities:
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Each student will get a computer and go to
http://nlvm.usu.edu/en/nav/frames_asid_335_g_4_t_3.html?from=category_g_4_t_3.html
This applet has students solving for missing items of a right triangle. Each student need to
do at least 5 problems each of which solve for a different missing piece of the triangle
and record their work on the given worksheet. They can use any of the information that
was talked about therefore they should not use the law of cosine or the law of sine since
we did not learn these yet.
At the end of class, students that finished will turn in their worksheet. If a student did not
finish they will have to finish it for homework and turn it in at the beginning of the next
class.
V. Adaptations:
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Students with IEP will be given more time if needed on any of the worksheets or less
problems to be determined by their IEP.
Any student that needs help with the technology will be given it.
Students that do not have access to the internet outside of class will be given another time
to finish the worksheet or a different take home activity if needed.
VI. Evaluation of Students:
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Students will be assess informally throughout the lesson. This will include the teacher
walking around and observing and answers students share with the class.
Students will also be assessed during the group discussion based on the information they
provide.
Students will be assessed and graded on the closing activity/homework assignment that
uses all the information they learned.
VII. Reflection
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There are two different types of technology in this lesson. One is students using the
calculator to calculate SIN, COS, and TAN of the angles in the triangle. The second is the
closing activity where students use the applet to solve for missing sides and angles using
SIN, COS, TAN, Pythagorean’s Theorem, and the sum of angles in a right triangle. Using
these two technologies is important to the lesson. Students will need the calculator to see
the connection between the ratio and angle. Also the applet ties everything together and
has students practicing what they learned. The only skills needed to use the calculator is
knowing how to use the trig buttons which is addressed in the worksheet. There are no
special skills needed for the applet. The calculator provides immediate feedback. Also the
applet is visual and helps guide student to use the information correctly. It also gives
immediate feedback if students get the answer wrong and if they select the wrong method
for solving for a specific element based on the information they have. I really like the
applet for this lesson because this is information that takes a while for students to
understand. Since this is the first time students are seeing this information, giving them
hints and guiding them to the correct answer helps them understand the information
without overwhelming them. The technology in this lesson is both mathematically
faithful and cognitively faithful. The worksheet that uses the calculator does offer an
opportunity for reflection. All prior knowledge students need to know is addressed in the
Do Now worksheet. Lastly the technology helps students understand the new knowledge
they are learning in this lesson.
References: This section should include all references in alphabetical order. All references
should be in APA format.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8
&ved=0CEYQFjAD&url=http%3A%2F%2Fmrsmightgeometry.weebly.com%2Fuploads
%2F8%2F5%2F8%2F6%2F8586304%2F2-3explore_explain_soh_cah_toa.doc&ei=FIlMU5KOMcab2QXxsIHoCw&usg=AFQjCNGXd
v_KVmyRNxDHkj5J8GIhYA_StA&sig2=JzAmPxPZYKCMcTm0WyiHA&bvm=bv.64764171,d.b2I