问题
解答题
化简求值: (1)
(2)log2.56.25+lg
|
答案
(1)∵sin(2π-α)=-sinα,sin(π+α)=-sinα,cos(-π-α)=-cosα
cos(
+α)=-sinα,sin(3π-α)=sinα,cos(π-α)=-cosαπ 2
∴sin(2π-α)sin(π+α)cos(-π-α) cos(
+α)sin(3π-α)cos(π-α)π 2
=
=-1-sinα•(-sinα)•(-cosα) -sinα•sinα•(-cosα)
(2)∵6.25=2.52,
=10-2,1 100
=ee
,1+log23=log261 2
∴log2.56.25+lg
+ln1 100
+21+log23e
=log2.52.52+lg10-2+lne
+2log26=2+(-2)+1 2
+6=1 2 13 2