(2)c? =a? +bc=4 1
(3) a? =c? -B? =400? a=20
(4)a=2? b= 1.5
First, multiple-choice questions: 1, B 2, a.
2. Fill in the blanks: 3.13;
4、60;
5、5
6、49
Third, answer the question: 7. Solution: BD? =3? +4? =5 BD=5
CD? =5? + 12? = 13 CD= 13
Extension: 8,
Note that two triangles under a diagonal square (such as the one with an area of 1) can be used to prove congruence.
Using Pythagorean theorem for one of the triangles, we can get
S 1+S2= 1
similar
S3+S4=3
Addition of two formulas
S1+S2+S3+S4 =1+3 = 4 (this question needs to be marked with capital letters and angles in the triangle you require).
I have done all these questions, and the answers are all right. Ask for adoption ~