Find: Tan 30o

• Cursor to 30o on T

Find: 15 Tan 30o

• Cursor to 30o on T
• Slide to 15 on CI (may need to flip your rule over for this step)

Find: Tan 60o

• Since our single T scale ends at 45 degrees, we must use a different method to find tangents of angles greater than 45 degrees. We will use the complement (30o) of the given 60o angle and find the inverse of its tangent, the cotangent, which is the same as tangent of 60o. This works because tan 60o = cot 30o= 1/tan 30o.
• Cursor to 30o on T (your rule may have a red 60o marking beside the mark for 30o.)

Find acute angle in triangle whose opposite side is 4.8 and adjacent side is 12.4

• Right index to 4.8 on D
• Cursor to 12.4 on CI (tangent is 0.387 on D at cursor)