# Verify the identity sinx/(1-cosx)=(1+cosx)/sinx.

hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted on

We need to verify that sinx/(1-xosx)= (1+cosx)/sinx

We know that sin^2(x) + cos^2(x)=1

==> sin^2(x)= 1-cos^2(x)

==> sin^2(x)= (1-cos(x))(1+cos(x))

==> (sinx)(sinx)= (1-cosx)(1+cosx)

Now divide by (sinx)(1-cosx)

==> sinx/(1-cosx)=(1+cosx)/sinx)

neela | High School Teacher | (Level 3) Valedictorian

Posted on

To verify whether sinx/(1-cosx) =(1+cosx)/sinx.

Solution:

We know that

sin^2x+cos^2x = 1. Or

sin^2x = 1-cos^2x = (1+cosx)(1-cosx). Dividing both sides by sinx(1-cosx) we get:

sinx/(1-cosx) = (1+cosx)/sinx

giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

To verify the identity, first, we have to cross multiply, so that:

sinx*sinx = (1-cosx)*(1+cosx)

We notice that, to the right side, the product will become a difference of squares:

(sinx)^2 = 1 - (cosx)^2

We'll move the term - (cosx)^2, to the left side, changing it's sign and we'll get:

(sinx)^2 + (cosx)^2 = 1

The relation above is true, being the fundamental formula of trigonometry.