Answer
Graphical approximation: $\approx$1.029
Calculator: $\approx$1.029639
Work Step by Step
For a point on the unit circle, the x-coordinate is $=\cos t$,
the y-coordinate is $\sin t$,
$\displaystyle \tan t=\frac{x}{y}$.
We estimate (see image below)
$\sin t\approx 0.72$
$\cos t\approx 0.7$
Dividing our estimates, $\tan$0.8$=\displaystyle \frac{x}{y}\approx$1.02857142857
while the calculator shows $\tan$0.8$\approx$1.02963855705
:
(see image below)
