Rectangle diagonal

The rectangle, one side of which is 5 cm long, is divided by a 13 cm diagonal into two triangles. Calculate the area of one of these triangles in cm².

Correct answer:

S =  30 cm²

Step-by-step explanation:

$$\begin{gathered} a=5\text{cm} \\ u=13\text{cm} \\ b=\sqrt{u^2-a^2}=\sqrt{13^2-5^2}=12\text{cm} \\ S=\frac{a\cdot b}{2}=\frac{5\cdot 12}{2}=30{\text{cm}}^2 \end{gathered}$$

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