Question

Is that not right? or am I just wrong cause it says that it is not right please help

Answer 1

98 cm²

Explanation:

The area of a circle is:

`A=\pi r^2`

A semicircle is half a circle therefore the area of a semicircle would be:

`A=(1)/(2)\pi r^2`

We can plug in the given values into the equation:

`A=(1)/(2)*3.142*(7.9)^2\\A=(1)/(2)*3.142*62.41\\A=(1)/(2)*196.09222 \\A=98.04611`

We need to round to TWO sigfigs meaning...

`A=98 \ cm^2`

Sigfig rules:

Nonzero numbers are significant

Trailing zeros are significant (only if there is a decimal point)

Any sandwiched zero is signification (Ex: 405 --> 3 sigfigs)