$\frac{\sin 1^{\circ}+\sin 2^{\circ}+\ldots+\sin 89^{\circ}}{2(\cos 1^{\circ}+\cos 2^{\circ}+\ldots+\cos 44^{\circ})+1} = $

Consider the two following statements $A$ and $B$,and identify the correct choice given in the answers :
$(A)$ In photovoltaic cells the photoelectric current produced is not proportional to the intensity of incident light.
$(B)$ In gas-filled photoemissive cells,the velocity of photoelectrons depends on the wavelength of the incident radiation.

The mass of a planet is half that of the earth and the radius of the planet is one-fourth that of earth. If we plan to send an artificial satellite from the planet,the escape velocity will be,(escape velocity on earth $v_e = 11 \ km \ s^{-1}$) (in $km \ s^{-1}$)

Let $A$ and $B$ be independent events with $P(A)=0.3$ and $P(B)=0.4$. Find $P(A | B)$.

The angle between the lines whose direction cosines are given by the equations $l^2+m^2-n^2=0$ and $l+m+n=0$ is

In which of the following is the sporophyte parasitic on the gametophyte?