SIN^2 A+SIN^2 B-SIN^2 A*SIN^2 B+COS^2 A*COS^2 b等于 1有谁会啊教教_数学解答

SIN^2 A+SIN^2 B-SIN^2 A*SIN^2 B+COS^2 A*COS^2 b等于 1
有谁会啊教教

人气：250 ℃　时间：2020-04-20 20:02:11

解答

SIN^2 A+SIN^2 B-SIN^2 A*SIN^2 B+COS^2 A*COS^2 B
=SIN^2 A+SIN^2 B-SIN^2 A*(1-COS^2 A)+(1-SIN^2 A)*COS^2 B
=SIN^2 A+SIN^2 B-SIN^2 A+SIN^2 ACOS^2 A+COS^2 B-SIN^2 A*COS^2 B
=SIN^2 A+SIN^2 B-SIN^2 A+COS^2 B
=SIN^2 B+COS^2 B
=1