## Trigonometry (11th Edition) Clone

$F(0)=0$ This means that the fraction of the moon's face illuminated by the sun is zero.
$F(t)=\frac{1}{2}(1-\cos t)$ For $F(0)$, the phase angle $t=0$. Substituting $t=0$ in the equation, $F(0)=\frac{1}{2}(1-\cos 0)$ $F(0)=\frac{1}{2}(1-1)$ $F(0)=\frac{1}{2}(0)$ $F(0)=\frac{1}{2}(0)$ $F(0)=0$ This means that the fraction of the moon's face illuminated by the sun is zero.