Hello, little classmate. In this trigonometric calculation, fill in 4,7 on the left and 1 1 on the right. Left 4+7= 1 1, right 4+1=15, bottom 7+ 1 1= 18. Fill it out yourself, add it yourself, and then calculate. In the future, if you encounter problems that you can't solve, you should think more and try a few times, and the answer will come out. Don't leave questions blank during the exam. Come on!