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Ex 8.4
Ex 8.4, 2 Important You are here
Ex 8.4, 3 (i) Important
Ex 8.4, 3 (ii)
Ex 8.4, 4 (i) [MCQ]
Ex 8.4, 4 (ii) [MCQ] Important
Ex 8.4, 4 (iii) [MCQ] Important
Ex 8.4, 4 (iv) [MCQ]
Ex 8.4, 5 (i) Important
Ex 8.4, 5 (ii)
Ex 8.4, 5 (iii) Important
Ex 8.4, 5 (iv) Important
Ex 8.4, 5 (v) Important
Ex 8.4, 5 (vi)
Ex 8.4, 5 (vii) Important
Ex 8.4, 5 (viii)
Ex 8.4, 5 (ix) Important
Ex 8.4, 5 (x)
Last updated at March 28, 2023 by Teachoo
Ex 8.4, 2 Write all the other trigonometric ratios of A in terms of sec A. cos A We know that cos A = / tan A We know that 1 + tan2 A = sec2 A tan2 A = sec2 A 1 tan A = ( 2 1) Here, A is acute (i.e. less than 90 ) & tan A is positive when A is acute tan A = ( 2 1) cot cot A = /( ) Putting value of tan A found above cot A = 1/( (sec^2 1 ) ) cosec A We know that 1 + cot2 A = cosec2 A cosec2 A = 1 + cot2 A cosec2 A = 1 + (1/( (sec^2 1 ) ))^2 cosec2 A = 1 + (1/( 2 1)) cosec2 A = ((1 ( 2 1) + 1)/( 2 1)) cosec2 A = (( 2 1 + 1)/( 2 1)) cosec2 A = ( 2 )/( 2 1) cosec A = (( 2 )/( 2 1)) cosec A = sec / ( 2 1 ) Here, A is acute (i.e. less than 90 ) & cosec A is positive when A is acute cosec A = sec / ( 2 1 ) sin A We know that sin A = /( ) sin A = 1/((sec / (sec^2 1 )) ) sin A = ( 2 1)/sec