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Chapter 8 Thigonmety,, TRIGONMETRY– Measurement technigues, of 3 sides of Right A., TRI - Three (3), GON - Sides, METRON (METRY) - Measure, Knowledge Reint, TRIGONMETRY is the study of relationships, between the sides and angles of a triangle ., Early astronomers used it to find out, the distances of stars and planets from, the earth, • Even today, most of the technologically, advanced methods used in Engineering, and Phystcal Sciences ave based on, tringle., trigonametrical concept.

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PYTHAGORAS THEOREM, 90, Base CB), B, In a right angled triangle, the 8quare of, the largest side (hypotenuse) is equal to the, Sum of two othex sides ( Perpendicular and Base)., H* = P°+ B, Square, of, A, Using Rythegoras theorem,, H* = °p*+8², H= ? P=4em,B= 3cm ở, 4em, %3D, 3cm, → H° = (4)" + (3), = 16+9, - 25 cm, >H=25 = 5cm, %3D, Hypotenuse (H), Perpendicular )

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#Trigonometrie Ratios, Ratios, of the Sides of a right a wrt its, acute angles, 39, Pandit Badri Prasad, PB P, H H B, Hari Hari Bol, Hypotenuse, A, Base, (Side adjacent to, ZA), Sin A = P, Cosec A = H., H., Cos A = B, Sec A =, H., A, B, tan A = L, cot A, Note:- 'o readas'theta', is an a cute, angle blw O and 90, lie, Perpendicular, (Side opposite to

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2. In fig ca), find tan P- cotR, Soln: we have , INLAPQR, H=13cm, P= 12cm , B=?, Using Pythagoras,, H = p² + B², 13cm (H), (P) 12cm, 2, B, (13)°= U2s*+ 8ª, figen), 2, 169, 144 + B, = 169- 144, B= J25 = 5cm = QR, from fig a)., tan P = P, 13cm (H), B) 12 cm, - tan P= 5, 12, Q, 5cm R, (P), Cot R= B, Hence, tan P- cot R = 0, > Cot R= 5, 12