sine rule 正弦定理.doc

LESSON PLAN FORMATCourse: Bilingual mathGrade Level: grade 2Teacher:BelaDate:Title: sine rule Content: Trigonometry PRE-LESSON PLANNINGLearning Objectives1. Learn to deduct the theorem of sine rule 2. Understand the meaning of sine rule3. Be able to use sine rule to solve questionDesign the AssessmentExercise page 198Design Assessment Rubric (if Needed)TEACHING THE LESSONVocabulary: Materials: IGCSE MATHEMATICS BOOKprocedure1. New knowledge Triangles that arent Right Angled To find unknown sides and angles in non-right angled triangles we can use one or both of 2 rules: the sine rule The cosine rule The next few slides prove the sine rule. The cosine rule is on the next presentation.The Sine RuleABC is a scalene triangle a, b and c are the sides opposite angles A, B and C Draw the perpendicular, h, from C to BA. In CAN,Sin A = In BCN,SinB= So, b sin A=h and asin B=hThe triangle ABC . . . . . can be turned so that BC is the base. We would then get So, We now have and So, The sine rule can be used in a triangle when we know One side and its opposite angle, plus One more side or anglee.g. Suppose we know p, q and angle Q in triangle PQR Tip: We need one complete “pair” to use the sine rule.The angle or side that we can find is the one that completes another pair. Solution: Use Solution: As the unknown is a side, we “flip” the sine rule over. The unknown side is then at the “top”. Application Problems Angle TDA =180 35 = 145 Angle DTA =180 170 = 10SUMMARY The sine rule can be used in a triangle when we know One side and its opposite angle, plusOne more side or angleWe write the sine rule so that the unknown angle or side is on the left of the equation If 2 sides and 1 angle are known we use: If 1 side and 2 angles are known we use: ExercisesCheck for Student Understanding by:Guided Practice Check for student understanding by: Some exercise Closing Activity Summarizing the LearningSTUDENT WORKIndependent PracticePOST LESSON ACTIVITIES Student AssessmentProvide feedback to the stude