Question

$r$ and $r^{\prime }$ denote the angles inside an equilateral prism, as usual; in degrees.
Consider that during some time interval from $t=0$ to $t=t,r^{\prime }$ varies with time as $r^{\prime }=$ $10+t^2$. During this time $r$ will vary as (assume that $r$ and $r^{\prime }$ are in degree)

• A. $50-t^2$
• B. $50+t^2$
• C. $60-t^2$
• D. $60+t^2$

Answer 1

Answer: (A)

In a prism: $r+r^{\prime }=A\Rightarrow r=A-r^{\prime }$
$\therefore r=60^{\circ }-\left(10+t^2\right)=50-t^2$