利用单位0.π/6,π/4,π/3,π/2的正弦余弦函数值,可以求出区间〖-7π/5,3π/5〗内哪些角的正弦余弦

利用单位0.π/6,π/4,π/3,π/2的正弦余弦函数值,可以求出区间〖-7π/5,3π/5〗内哪些角的正弦余弦函数值
解析：∵区间〖-7π/5,3π/5〗
Sin(-4π/3)=-Sin(4π/3)=Sin(π/3)=√3/2,cos(-4π/3)=-1/2
Sin(-5π/4)=√2/2,cos(-5π/4)=-√2/2
Sin(-7π/6)=1/2,cos(-7π/6)=-1/2
Sin(-π)=0,cos(-π)=-1
Sin(-5π/6)=-1/2,cos(-5π/6)=-√3/2
Sin(-3π/4)=-√2/2,cos(-3π/4)=-√2/2
Sin(-2π/3)=-√3/2,cos(-2π/3)=-1/2
Sin(-π/2)=-1,cos(-π/2)=0
Sin(-π/3)=-√3/2,cos(-π/3)=1/2
Sin(-π/4)=-√2/2,cos(-π/4)=√2/2
Sin(-π/6)=-1/2,cos(-π/6)=√3/2
Sin(0)=0,cos(0)=1
Sin(π/6)=1/2,cos(π/6)=√3/2
Sin(π/4)=√2/2,cos(π/4)=√2/2
Sin(π/3)=√3/2,cos(π/3)=1/2
Sin(π/2)=1,cos(π/2)=0

∵OP的绝对值=根号(-2)²+y²
∴sina=y/根号（-2）²+y²=2根号2/5
所以y=4根号34/17