If `sintheta_1sintheta_2-costheta_1costheta_2+1=0,` then the value of `tan((theta_1)/2)cot((theta_2)/2)` is equal to `-1` (b) 1 (c) 2 (d) `-2`

Options

A. `a^(2)+b^(2)ge4`
B. `a^(2)+b^(2)le4`
C. `a^(2)+b^(2)ge3`
D. `a^(2)+b^(2)le2`

Answer

B

Explanation

`sintheta_(1)-sin theta_(2)=a,cos theta_(1)+cosheta_(2)=b`
`rArr a^(2)+b^(2)=2+2cos(theta_(1)+theta_(2))`
`rArr 0lea^(2)+b^(2)le4`