Inverse sine

Why inverse sine?

Rise ÷ slant gives the sine of the angle. sin⁻¹ turns that ratio back into degrees.

Try it · 3 ft rise, 5 ft slant

Both measurements are in feet, so divide their numbers.

1. Start fresh

   Press Clear entry, then Clear entry.C→C

2. Rise ÷ slant

   Press 3, then Divide, then 5, then Equals.3→÷→5→=

3. Find the angle

   Press Second, then Inverse sine.2nd→sin⁻¹

Also useful for

Ramp angles, diagonal supports, pipe offsets and sloping duct sections when the rise and slant are easier to measure than the run.

Remember

Use matching units. In a right triangle the slant is the longest side, so rise ÷ slant cannot exceed 1. sin⁻¹ means find the angle, not 1 ÷ sin.

Start a new calculation

1. Press Clear entry, then Clear entry.C→C

Calculate

1. sin ratio

   Press .57544, then Second, then Inverse sine..57544→2nd→sin⁻¹

Start a new calculation

Use 2nd if a unit is above its button.

1. Start fresh

   Press Clear entry, then Clear entry.C→C

2. Press the keys

   Press Select length units.Length

Calculate

1. Offset

   Press 8, then inches, then Divide.8→Inch→÷

2. Slant

   Press 25, then inches, then Equals.25→Inch→=

3. Find the angle

   Press Second, then Inverse sine.2nd→sin⁻¹