Question

Astronomy Cepheid stars appear to pulsate because they expand and contract in size. In its contracted phase, the Cepheid star Zeta Geminorum is 51 million miles across. This is 5 million miles less than the star’s distance across in its expanded phase. Find the distance across Zeta Geminorum in its expanded phase.

Short answer

The distance across Zeta Geminorum in its expanded phase is$56$million miles.

Step-by-step solution

Step-1-Writing formula from given information

Let$x$be Size of Zeta Geminorum in expanded phase.

From the given information, we can say that,

Size of Zeta Geminorum in expanded phase$=$ Size in Zeta Geminorum contracted phase $+$Size less than the star’s distance across in it expand phase.

Step-2-Solving for value of x

On substituting values, we get,

$\begin{array}{l}x=51+5\\ x=56\end{array}$

Step-3- Conclusion 

Therefore, the size of Zeta Geminorum in expanded phase$=x=56$million miles.