The monotonic increasing interval of y=sin(x+π/4) satisfies:

2kπ-π/2 & lt； = x+π/4 & lt； =2kπ+π/2

So the monotonically increasing interval is [2kπ-3π/4, 2kπ+π/4], and k is an integer.

If the chord length of the central angle 1 radian is 2, then:

2Rsin( 1/2)=2

R= 1/sin( 1/2)

The arc length is 1/sin( 1/2)