P69 1。 Parallelogram 2. 12cm 16cm 3. Rectangle 4. Two-thirds root number 2 5. An isosceles triangle of 50 degrees. Two-thirds of the positive and negative roots are 33-17.m >; 3/2 8.3/2 16 The number of roots is 3 9.80 degrees.

1 1 . c 12 . c 13。 A.. 14.C 15。 D 16。 B 17。 A 18。 B 19。 B

P761.122.112.5 degrees 3.90 degrees 4. Isosceles triangle 5.24, 25

7.C