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सिद्ध कीजिए कि - `tan^(-1)1+tan^(-1)2+tan^(-1)3=pi` |
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Answer» `LH.S.=tan^(-1)+tan^(-1)2+tan^(-1)3` `=(pi)/(4)+((pi)/(2)-cot^(-1)2)+((pi)/(2)-cot^(-1)3),` `[because tan^(-1)x=(pi)/(2)-cot^(-1)x" सभी "x in R " के लिए "]` `=(pi)/(4)+pi-(cot^(-1)2+cot^(-1)3)` `=(pi)/(4)+pi-[tan^(-1)((1)/(2))+tan^(-1)((1)/(3))]` `" "[because cot^(-1)x=tan^(-1)((1)/(x))]` `=(pi)/(4)+pi-tan^(-1)(((1)/(2)+(1)/(3))/(1-(1)/(2)xx(1)/(3)))` `=(pi)/(4)+pi-tan^(-1)(((5)/(6))/((5)/(6)))` `=(pi)/(4)+pi-tan^(-1)(1)` `=(pi)/(4)+pi-(pi)/(4)` `=pi=R.H.S." "` यही सिद्ध करना था । |
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