Flag Trigonometry> if Cos A+Cos 2 A=1 THEN FIND Sin 2 A+Sin ...
question mark

if Cos A+Cos2A=1 THEN FIND Sin2A+Sin4A=?

nileena , 10 Years ago
Grade
anser 4 Answers
Nishant Vora

Last Activity: 10 Years ago

Hello Student, please find the solution:

Cos A+Cos2A=1
=> cosA = 1 – cos2A = sin2A

So, Required is
sin2A + sin4A
= Cos A+Cos2A
=1

I hope the solution is clear
Thanks.

Eshika gupta

Last Activity: 6 Years ago

Since cos A + cosA=1 
Now,cosA= 1-cos2A=sin2A
Then  taking L.H.S. sin2A+sin4A
=Sin2A(1+sin2A)
=CosA(1+cosA)
CosA+cos2A=1(given)
L.H.S =1 Hence proved

Rishab

Last Activity: 6 Years ago

Cosa+cos^2=1
Cosa+1-sin2a=1
Cosa-sin2a=0
Cosa=sin2a
Squaring both side 
Cos2a=sin4a
Sin2a+sin4a=1
Sin2a+cos2a=1
1=1

Rahul ram

Last Activity: 5 Years ago

CosA+cos^2=1
CosA+1-Sin^2A=1
CosA-Sin^2A=0
CosA=Sin^2A
Sq both side 
Cos^2A=Sin^4A
1-Sin^2A=Sin^4A
1=Sin^4A+Sin^2A
Hence ,
Ans is 1....
 

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments