Respuesta :

devishri1977

Answer:

Step-by-step explanation:

Cos²y + Sin² y = 1

Therefore,   Cos² y = 1 - Sin² y

LHS = Cos² y - Sin² y

       = 1 - Sin² y - Sin² y    {Combine like terms}

       = 1 - 2sin² y  = RHS

Mashfia

    cos²y - sin²y = 1 - 2sin²y

or, cos²y - sin²y + 2sin²y = 1

or, cos²y + sin²y = 1 [It's a formula]

(Is that what you mean by simplify?)