Sunday, May 10, 2015

Prove sinx/secx+tanx-1 + cosx/cosec x+cotx-1 = 1

If the given expression is sinx/(sec x+tan x-1) +
cosx/(cosec x+cot x-1)=1, we'll do the following steps:


sin
x/(1/cos x+  sin x/cos x - 1) + cos x/(1/sin x + cos x/sin x - 1) =
1


We've replaced sec x=1/cos x; tan x = sin x/cos x ; cosec
x = 1/sin x and cot x = cos x/sin x


sin x/(1/cos x+  sin
x/cos x - 1) + cos x/(1/sin x + cos x/sin x - 1) = 1


sin
x*cos x/(1+sin x- cos x) + sin x*cos x/(1 + cos x - sin x) =
1


We'll multiply the 1st fraction by (1 + cos x - sin x)
and the 2nd fraction by (1+sin x- cos x):


sin x*cos x(1 +
cos x - sin x + 1+sin x- cos x)/(1 + cos x - sin x)*(1+sin x- cos x) =
1


We'll eliminate like terms within brackets and we'll
multiply the right side by (1 + cos x - sin x)*(1+sin x- cos
x):


2 sin x*cos x = (1 + cos x - sin x)*(1+sin x- cos
x)


We'll remove the
brackets:


2 sin x*cos x = 1+sin x- cos x + cos x + sin
x*cos x - (cosx)^2 - sin x - (sin x)^2 + sin x*cos x


But
(sin x)^2 + (cosx)^2 = 1


2 sin x*cos x = 1 - 1 + 2sin x*cos
x


2 sin x*cos x =  2sin x*cos
x


Since both sides are equal, then the given
expression represents an identity.

No comments:

Post a Comment

Film: 'Crocodile Dundee' directed by Peter FaimanHow are stereotypical roles upheld and challenged?

One of the stereotypes that is both upheld and challenged is the role of the damsel in distress. Sue is supposed to be the delic...