What is the study of living organisms called?

The equation of a pair of lines is given by a second-degree homogeneous equation. If one of them is perpendicular to the line $x+2y+7=0$ and the other line is parallel to the line $3x+4y+5=0$,then the equation of that pair of lines is:

If $y=a e^x+b e^{-x}+c$,where $a, b, c$ are parameters,then $y^{\prime \prime \prime}$ is equal to

At a certain place,the horizontal component of the Earth's magnetic field is $B_0$ and the angle of dip is $45^o$. The total intensity of the field at that place will be:

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

Which of the following compounds will exhibit geometrical isomerism?