A group of students measured the height of a big tree. Due to limited tools, they only measured the shadow length of this tree as 5 meters. At the same time, they also measured the height of a small tree next to it was 1.4 meters, and the shadow length was 1 meter. Please calculate this tree The height of the tree.
某小组同学测量一棵大树的高度，因工具有限，只测得了这棵树的影长是5米，同时还测得旁边一棵小树高1.4米，影长1米，请算出这棵大树的高度．
<gadget id="calculator">1 / 1.4</gadget>
<output>0.714286</output>

<gadget id="calculator">5 / 0.714286</gadget>
<output>6.999997</output>

<result>6.999997</result>