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)