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Example 3 - Chapter 8 Class 10 Introduction to Trignometry (Term 1)
Last updated at March 29, 2023 by Teachoo
Examples
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Example 3 You are here
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Example 6
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Example 8 Important
Example 9 Deleted for CBSE Board 2023 Exams
Example 10 Important Deleted for CBSE Board 2023 Exams
Example 11 Important Deleted for CBSE Board 2023 Exams
Example 12
Example 13 Important
Example 14 Important
Example 15 Important
Chapter 8 Class 10 Introduction to Trignometry
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Transcript
Example 3 Consider ACB, right-angled at C, in which AB = 29 units, BC = 21 units and ABC = (see fig.). Determine the values of (i) cos2 + sin2 , Step1 : Finding sides of triangle In right triangle ABC, using Pythagoras theorem (Hypotenuse)2 = (Height)2 + (Base)2 AB2 = AC2 + BC2 AC2 = AB2 BC2 AC2 = (29)2 (21)2 Using a2 b2 = (a + b) (a b) AC2 = (29 21) (29 + 21) AC2 = (8) (50) AC = (8 50) AC = 400 AC = 20 Step 2 : Finding sin , cos We have to find out , cos2 + sin2 Putting values = (21/29)^2+(20/29)^2 = ((21)2 + (20)2)/292 = (441 + 400)/841 = 841/841 = 1 So, cos2 + sin2 = 1 Example 3 Consider ACB, right-angled at C, in which AB = 29 units, BC = 21 units and ABC = (see fig.). Determine the values of (ii) cos2 sin2 . cos2 sin2 Putting values = (21/29)^2 (20/29)^2 = ((21)2 (20)2)/292 Using a2 b2 = (a + b) (a b) = ((21 + 20)(21 20))/292 = ((41)(1))/841 = 41/841
