题目

如图，等腰直角△ABC和等边△AEF都是半径为R的圆的内接三角形．（1）求AF的长. （2）通过对△ABC和△AEF的观察，请你先猜想谁的面积大，再证明你的猜想． 答案：【答案】（1）AF=R；（2）S△ABC＜S△AEF.【解析】（1）连接OF，过O作OG⊥AF于G，在直角△OGF中，利用三角函数即可求解；（2）根据外接圆的半径是R，即可求得等腰直角△ABC和等边△AEF的面积，即可作出比较．（1）如图，连接OF，过O作OG⊥AF于G，OF=R，又∵△AEF为等边三角形，∴∠AOF=120°，∴∠GOF=60°，在Rt选择适当的单词填空。was were is are be ana messy mess at onwas were is are be ana messy mess at on1. The cupboards __________ tidy yesterday morning.2. Just now the bin _________ empty.3. The sink ____________ full now.4. Today the walls _________ clean.5. There was a party at their house______ Sunday ______ 11:00. 6. Clean your kitchen and _______ healthy.7. What a _______ the kitchen is!8. Look! The kitchen is __________.9. There was _________ old fridge.10. This is ________ tidy living room.