Math, asked by dratul353, 11 months ago

if tan²A=1+2tan²B prove that cos2B=1+2cos2A

dratul353: thank for trying it

dratul353: i done it

helpme10: ok

helpme10: will u please tell me how u did

dratul353: o yes

dratul353: cos2B=1+2cos2A=1+2×(1-tan²A/1+tan²B)=1+(2{1-[1+2tan²B]}/{1+[1+2tan²B]}=1+(-4tan²B)/(2+2tan²B)=1+(-4tan²B)/(2+2tan²B)=(2+2tan²B-4tan²B)/(2+2tan²B)=(2-2tan²B)/(2+2tan²B)=2(1-tan²B)/2(1+tan²B)=cos2B

dratul353: plz understand it with cool mind

helpme10: arey yrr ...silly mistake kr di

dratul353: kaha par

dratul353: yeha likhne mein galte hogi copy ka photo agar veg shakta to per shamaj jate...

Answers

Answered by ashu68713

search in Google assistant or else in internet

Answered by zainab28204

that's your answer hope it's helpful to you

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