三角函数求起终边相等有一下四组角：⑴kπ+π/2;⑵kπ-π/2;⑶2kπ±π/2;⑷-kπ+π/2(k∈Z)其中终边相同的是A.⑴⑵B.⑴⑵⑶C.⑴⑵⑷D.⑴⑵⑶⑷

Question

三角函数求起终边相等
有一下四组角：⑴kπ+π/2;⑵kπ-π/2;⑶2kπ±π/2;⑷-kπ+π/2(k∈Z)其中终边相同的是
A.⑴⑵
B.⑴⑵⑶
C.⑴⑵⑷
D.⑴⑵⑶⑷

Answer 1

⑴kπ+π/2(k∈Z)={...-5π/2,-3π/2,-π/2,π/2,3π/2,5π/2,...}
⑵kπ-π/2(k∈Z)={...-5π/2,-3π/2,-π/2,π/2,3π/2,5π/2,...}
⑶2kπ±π/2(k∈Z)={...-5π/2,-3π/2,-π/2,π/2,3π/2,5π/2,...}
⑷-kπ+π/2(k∈Z)={...-5π/2,-3π/2,-π/2,π/2,3π/2,5π/2,...}
所以其实(1)(2)(3)(4)的终边是相同的
所以选D