Math, asked by Keitie, 11 months ago

Show that :

Cos2a = 1- 2sin^2a

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Answers

Answered by Stera
6

Here's your solution:

 \cos(2a)  \\  \\  =  \cos(a + a)  \\  \\  =  \cos(a)  \cos(a) -  \sin(a)  \sin(a) \\  \\  =  { \cos}^{2}  a \:  -   { \sin }^{2} a \\  \\  = 1 -   { \sin }^{2} a -  { \sin }^{2} a \: (since \:  \:   {sin}^{2} a +  {cos}^{2} a = 1) \\  \\  = 1 - 2 {sin}^{2} a

Hence Shown


Keitie: thanx
Stera: welcome ^_^
Answered by Anonymous
10

Answer is in attachment

Hope this will help ✌

Attachments:

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Anonymous: wello❤
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