將點(diǎn)M（3/4π,0）代入得：cos (3/4π•w)=0,
3/4π•w=kπ+π/2,k∈Z.
w=4K/3+2/3,k∈Z.
函數(shù)f(x)=cos wx(w>0)在區(qū)間【0,π/2】上是單調(diào)函數(shù),
X∈【0,π/2】,wx∈【0,wπ/2】.
原點(diǎn)右側(cè)含有0的余弦函數(shù)單調(diào)區(qū)間長度最大時(shí),區(qū)間是【0,π】.
因?yàn)楹瘮?shù)f(x)=cos wx(w>0)在區(qū)間【0,π/2】上是單調(diào)函數(shù),
所以【0,wπ/2】包含于【0,π】,
即wπ/2≤π,w≤2.
又因w=4K/3+2/3,k∈Z.
所以k=0時(shí),w=2/3.
K=1時(shí),w=2.