Math, asked by dratul353, 1 year 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
4
search in Google assistant or else in internet
Answered by zainab28204
3

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

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