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Lesson Plans (1) A detailed description of the instruction for teaching one or more concepts or skills. Classroom Resources (1)


ALEX Lesson Plans  
   View Standards     Standard(s): [MA2015] PRE (9-12) 35 :
35 ) (+) Derive the formula A = (1/2)ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side. (Apply formulas previously derived in Geometry.) [G-SRT9] (Alabama)

Subject: Mathematics (9 - 12)
Title: Triangle Area: No Height?--Use the Sine
Description:

This lesson will lead students through a review of the proof of the Law of Sines. This proof will remind them that they can use the right triangle relationship for Sine to find the height of a triangle. They will then apply this knowledge to find the area of a triangle when given two sides and an included angle. Finally, they will be asked to find the area when no values are given. This result should produce the Area Formula for a triangle given two sides and the included angle.

This lesson results from the ALEX Resource Gap Project.




ALEX Classroom Resources  
   View Standards     Standard(s): [MA2015] GEO (9-12) 22 :
22 ) (+) Prove the Law of Sines and the Law of Cosines and use them to solve problems. [G-SRT10]

[MA2015] GEO (9-12) 23 :
23 ) (+) Understand and apply the Law of Sines and the Law of Cosines to find unknown measurements in right and non-right triangles (e.g., surveying problems, resultant forces). [G-SRT11]

[MA2015] PRE (9-12) 35 :
35 ) (+) Derive the formula A = (1/2)ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side. (Apply formulas previously derived in Geometry.) [G-SRT9] (Alabama)

Subject: Mathematics (9 - 12)
Title: Precalculus and Advanced Topics Module 4, Topic B: Trigonometry and Triangles
URL: https://www.engageny.org/resource/precalculus-and-advanced-topics-module-4-topic-b-overview
Description:

Students derive sophisticated applications of the trigonometric functions in Module 4, Topic B including the area formula for a general triangle, the law of sines, the law of cosines, and Heron’s formula. They use previous knowledge and apply their understanding of the Pythagorean theorem and oblique triangles to discover these formulas while analyzing patterns. Finally, as students investigate force diagrams and paths across rivers, they solve survey and elevation problems and revisit vectors.

Note: This module is identified as Precalculus and Advanced Topics in the EngageNY curriculum. It also corresponds to the Geometry Alabama Course of Study.



ALEX Classroom Resources: 1

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