设<img src="https://static.zxtiku.com/wangke/imgs/topic/7db5b259489c65ac701ac634e67ba9c0.jpg"/>的三边长分别为<img src="https://static.zxtiku.com/wangke/imgs/topic/b8a6ea0d5767703d2635e9bced1adaff.jpg"/>.<img src="https://static.zxtiku.com/wangke/imgs/topic/a70ed2f490b0337259f57f193be43896.jpg"/>的面积为<img src="https://static.zxtiku.com/wangke/imgs/topic/aa11ddb137d71f176f4288195e53525b.jpg"/>,内切圆半径为<img src="https://static.zxtiku.com/wangke/imgs/topic/e3e6647c9a7ddc24a17e1a8a3b94cae1.jpg"/>,则<img src="https://static.zxtiku.com/wangke/imgs/topic/9b4ddd67574fc11c47bf2bcb14f7457c.jpg"/>. 类比这个结论可知:四面体<img src="https://static.zxtiku.com/wangke/imgs/topic/e82c6ad9c38c1e6d952d3fcbc447bd95.jpg"/>的四个面的面积分别为<img src="https://static.zxtiku.com/wangke/imgs/topic/53887e85bbc2c651737eab933f188219.jpg"/><img src="https://static.zxtiku.com/wangke/imgs/topic/506c4182cbf17112630864580b35c22c.jpg"/>.内切球的半径为r<img src="https://static.zxtiku.com/wangke/imgs/topic/2cf61ea78aeeb1aca2a5b695c609d89d.jpg"/>,四面体<img src="https://static.zxtiku.com/wangke/imgs/topic/486024bf31c02944eb7a683c000d954c.jpg"/>的体积为<img src="https://static.zxtiku.com/wangke/imgs/topic/43f1e1e79aee7e73bf8b63d60191b758.jpg"/>,则<img src="https://static.zxtiku.com/wangke/imgs/topic/eedaa63bdc26a99f9c0f8ebef3b9e30d.jpg"/>=( )。<br/> A、<img src="https://static.zxtiku.com/wangke/imgs/topic/a9890ff8a0fd0bc512932306aca10664.jpg"/><br/> B、<img src="https://static.zxtiku.com/wangke/imgs/topic/9f85ce31dec55f6c1bb63fd19f6f8fc1.jpg"/><br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/aee3a76a5a132a8509671c2444172799.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/e830223c08a5628a2eb9d14330413796.jpg"/>