Find the value of 2sin(alpha)*cos(alpha)

by **sin cos** » Tue Mar 15, 2011 9:14 am

Let's [tex]sin \alpha + cos \alpha = a[/tex]
Find the value of the expression: [tex]2sin\alpha cos\alpha[/tex]

by **Guest** » Sat May 21, 2011 4:05 pm

if sinx+cosx=a than [tex](sinx+cosx)^2=a^2[/tex]
[tex]sin^2x+cos^2x +2sinxcosx=a^2[/tex]
[tex]2sinxcosx=a^2-1[/tex]

by **sin cos** » Tue May 31, 2011 4:10 pm

Simplify the trigonometric expression:
[tex]\frac{1 - sin2x }{1 + sin2x }[/tex]

by **Guest** » Sun Jun 05, 2011 6:31 am

sin cos wrote:Simplify the trigonometric expression:
[tex]\frac{1 - sin2x }{1 + sin2x }[/tex]

= (1-2sinx*cosx)/(1+2sinx*cosx)=(1-a*a+1)/(1+a*a-1)=(2-a*a)/a*a