$H^{+}$,$D^{+}$,and $T^{+}$ differ in all of the following $EXCEPT$ one. Identify it.

If $a \sin^2 \theta + b \cos^2 \theta = c$,then $\tan^2 \theta$ is equal to

The number of circles that touch all the three lines $x+y-1=0$,$x-y-1=0$,and $y+1=0$ is

If three points $A, B$ and $C$ have position vectors $(1, x, 3)$,$(3, 4, 7)$ and $(y, -2, -5)$ respectively and if they are collinear,then $(x, y) = $

Observe the following statements :
$I$. The circle $x^2+y^2-6x-4y-7=0$ touches the $y$-axis.
$II$. The circle $x^2+y^2+6x+4y-7=0$ touches the $x$-axis.
Which of the following is a correct statement?

$A$ person standing on a rotating platform has his hands lowered. He suddenly outstretches his arms. The angular momentum