⑴把sin10sin30sin50sin70变成
sin10sin30sin50sin70×8cos10÷8cos10
＝4sin20sin30sin50cos20÷8cos10
=2sin40×sin30×cos40÷8cos10
＝sin80×sin30÷8cos10
＝0.5÷8=0.0625
⑵等于
求sin10sin30sin50sin70的值(最好有过程),还有的就是sin20sin60sin100sin140=c
⑴把sin10sin30sin50sin70变成
sin10sin30sin50sin70×8cos10÷8cos10
＝4sin20sin30sin50cos20÷8cos10
=2sin40×sin30×cos40÷8cos10
＝sin80×sin30÷8cos10
＝0.5÷8=0.0625
⑵等于