By geometrical interpretation, prove that
`tan(alpha+beta)=(tanalpha+tanbeta)/(1-tanalphatanbeta)`.

(1+tanalphatanbeta)^2+(tanalpha-tanbeta)^2=

(1+tanalphatanbeta)^2+(tanalpha-tanbeta)^2=

By geometrical interpretation, prove that (i) sin(alpha+beta)=sin alpha cos beta+sinbeta cosalpha (ii) cos(alpha+beta)=cosalpha cosbeta -sin alpha sinbeta

If cos theta=(cos alpha cos beta)/(1-sin alpha sin beta), prove that one value of (tan) theta/2=(tan alpha/2-tan beta/2)/(1-t a n alpha/2 tan beta/2).

(1+tan alpha tan beta)^2 + (tan alpha - tan beta)^2 =

If cos theta=(cos alpha cos beta)/(1-sin alpha sin beta), prove that one value of tan (theta/2)=(tan (alpha/2)-tan (beta/2))/(1-tan (alpha/2) tan (beta/2)).

If acos2theta+bsin2theta= c, alpha and beta as its roots , then prove that tanalpha+t a nbeta=(2 b)/(a+c) , tanalpha*t a nbeta=(c-a)/(c+a) , tan(alpha+beta)=b/a

If alpha+beta=pi/4 then (1+tan alpha)(1+tan beta)=

Prove that: tan(alpha+beta)tan(alpha-beta)=(sin^2 alpha-sin^2 beta)/(cos^2 alpha-sin^2 beta)

A tree standing on horizontal plane is leaning towards east. At two points situated at distances a and b exactly due west on it, angles of elevation of the top are respectively alpha and beta . Prove that height of the top from the ground is ((b-a).tanalpha.tanbeta)/(tanalpha-tanbeta)