根号三倍的tan11+根号三倍的tan19+tan11·tan19还有知道tan(a+b)=5 tan(a-b)=3 那么tan2a等于多少?怎么算?
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根号三倍的tan11+根号三倍的tan19+tan11·tan19还有知道tan(a+b)=5 tan(a-b)=3 那么tan2a等于多少?怎么算?
根号三倍的tan11+根号三倍的tan19+tan11·tan19
还有知道tan(a+b)=5 tan(a-b)=3 那么tan2a等于多少?怎么算?
根号三倍的tan11+根号三倍的tan19+tan11·tan19还有知道tan(a+b)=5 tan(a-b)=3 那么tan2a等于多少?怎么算?
因为tan(11+19)=(tan11+tan19)/(1-tan11*tan19)
所以tan11+tan19=[tan(11+19)]*(1-tan11*tan19)
=(1-tan11*tan19)/根号3
√3tan11°+√3tan19°+tan11°tan19°
=√3(tan11°+ tan19°)+tan11°tan19°
==√3tan(1...
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因为tan(11+19)=(tan11+tan19)/(1-tan11*tan19)
所以tan11+tan19=[tan(11+19)]*(1-tan11*tan19)
=(1-tan11*tan19)/根号3
√3tan11°+√3tan19°+tan11°tan19°
=√3(tan11°+ tan19°)+tan11°tan19°
==√3tan(11°+ 19°)(1-tan11°tan19°)+tan11°tan19°
=1
tan2a=tan[(a+b)+(a-b)]=
[tan(a+b)+tan(a-b)]/[1-tan(a+b)*tan(a-b)] =(3+5)/(1-3*5)=-4/7
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