<wj-body class="wj-body"><div class="wj-math wj-math-block"><span class="wj-equation-number"><span class="wj-equation-paren wj-equation-paren-open">(</span>1<span class="wj-equation-paren wj-equation-paren-close">)</span></span><code class="wj-math-source wj-hidden" aria-hidden="true">A = \pi \cdot r^2</code><wj-math-ml class="wj-math-ml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><mi>A</mi><mo>=</mo><mi>π</mi><mo>·</mo><msup><mi>r</mi><mn>2</mn></msup></math></wj-math-ml></div></wj-body>