Question

sina×sinb-cosa×cosb+1=0 then 1+cosa×tanb=​

Answer 1

Answer:

Step-by-step explanation:

Hint: use sina*sinb= ½ * (cos(a-b) – cos(a+b)),

and cosa*cosb = ½ * (cos(a-b) + cos(a+b)),

simplify and you will get, a + b = 2n*pi,

just put in second equation

Aliter

Solution

sinasinb-cosacosb=-1

so,cos(a+b)=-1

so,a+b=180 or a=180-b

1+tanbcota

1+tanb/tana

(tana+tanb)/tana

(tan(180-b)+tanb)/tana

(-tanb+tanb)/tana

=0