Fix the wrong number of solutions

01

Press these keys

WINDOWGRAPHintersect / zero

02

Walkthrough

1
Use the full domain
Set a window that covers the entire stated interval.
2
Find one at a time
Zero, intersect and Solver return a solution near the bracket or starting value; repeat elsewhere.
3
Inspect discontinuities
Do not count vertical-asymptote drawing artifacts as solutions.

03

Worked example

sin x=0.4 on 0≤x≤2π gives only 0.412 from inverse sine.

NORMAL FLOAT AUTO REAL MPsecond intersection near 2.730

AnswerThere are two solutions in the interval.