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Answers to the eighth-grade math book published by Beijing Normal University
Seriously do the exercises in the eighth grade math book and check them carefully! I sorted out the answers of the eighth grade math book Beijing Normal University Edition, hoping to help everyone!

In the eighth grade, I practiced on page (1) 10 of Beijing Normal University.

1. Solution (1)(4) The length of three sides of a right triangle can be taken; (2)(3) cannot be used as the length of three sides of a right triangle.

Reason: (1)9? + 12? = 15? , (4) 15? +36? =39? All satisfy the trilateral relationship of right triangle;

(2) 12? + 1822? , (3) 12? +3536? , does not satisfy the trilateral relationship of a right triangle.

2. There are four solutions, in which △ Abe, △ BEF, △ BCF and △ DEF are right triangles.

The verification that △BEF is a right triangle is as follows: According to Pythagorean theorem, BE? =20,EF? =5,BF? =BC? +CF? = 16+9=25, which means BE? +EF? =BF? So △BEF is a right triangle.

Which of the other three triangles? First,? c,? D is a right angle.

Answers to Grade 8 Mathematics Book of Beijing Normal University Edition (2) Page 29

Answers to the eighth grade mathematics books published by Beijing Normal University (3)