Use 90 cm wire to form a right triangle. The ratio of the lengths of the three sides of this triangle is 3:4:5. What is the area of this triangle in square centimetres.
用90厘米的铁丝围成一个直角三角形，这个三角形三条边长度的比是3：4：5．这个三角形的面积是多少平方厘米．
<gadget id="calculator">5 + 3 + 4</gadget>
<output>12</output>

<gadget id="calculator">90 / 12</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">(15/2) * 3</gadget>
<output>45/2 = around 22.5</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(45/2) * 30 * (1/2)</gadget>
<output>675/2 = around 337.5</output>

<result>675/2 = around 337.5</result>