Which of the following wiring diagrams could be used to experimentally determine $R$ using Ohm's law? Assume an ideal voltmeter and an ideal ammeter.

If in a $\triangle ABC$,$r_3 = r_1 + r_2 + r$,then $\angle A + \angle B$ is equal to (in $^{\circ}$)

$\sinh^{-1}(2^{3/2})$ is equal to :

If $x=\log _{0.1} 0.001$ and $y=\log _9 81$,then $\sqrt{x-2 \sqrt{y}}$ is equal to

Starting from rest, a body slides down a $45^{\circ}$ inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is:

Venus appears brighter than other stars because