Question

If cosA+cos²A=1 then sin²A+sin²A=?​

Answer 1

Answer:

1

Step-by-step explanation:

Cos A+Cos2A=1

=> cosA = 1 – cos2A = sin2A

So, Required is

sin2A + sin4A

= Cos A+Cos2A

=1

(The question you have posted is wrong... It's sin2A + sin4A. I have answered accordingly.)

Hope this helps :)

Answer 2

given,

$cos a + cos { {}^{} }^{2} a = 1 \\ now \: \\ cos \: a = 1 - cos {}^{2} a \\ we \: know \: that \\ sin {}^{2} a + cos {}^{2} a = 1 \\ now \\ sin {}^{2} a = 1 - cos {}^{2} a \\ we \: already \: know \: that \: cos \: a = 1 - cos {}^{2} a \\ now \: substitute \\ so \\ \: sin {}^{2} a + sin {}^{2} a = cos \: a + cos \: a \\ so \\ sin {}^{2} a + sin {}^{2} a = 2cos \: a$