SOHCAHTOA Solver
SOHCAHTOA is the famous memory aid for right-angle trigonometry: SOH means sine equals opposite over hypotenuse, CAH means cosine equals adjacent over hypotenuse, and TOA means tangent equals opposite over adjacent. Between them, these three ratios connect any angle in a right triangle to any two of its sides. If you know one angle and one side, every other measurement in the triangle is determined. This calculator puts that to work: enter the angle, tell it which side you know (the opposite, the adjacent, or the hypotenuse), enter its length, and it solves all three sides and the other acute angle instantly. The right angle is always the third angle, so the two acute angles add to 90 degrees, which means knowing one gives you the other automatically. The calculator picks the right ratio for each case. If you know the hypotenuse: opposite = hypotenuse times sine, adjacent = hypotenuse times cosine. If you know the opposite: hypotenuse = opposite divided by sine, adjacent = opposite divided by tangent. If you know the adjacent: hypotenuse = adjacent divided by cosine, opposite = adjacent times tangent. Seeing these results calculated for your specific inputs makes the logic clear and concrete, which is why this tool is well suited to students working through trigonometry for the first time. It is also genuinely useful for practical problems in construction, surveying, and navigation, where you know a slope angle and one measurement and need the rest. Enter any angle between 0 and 90 degrees exclusive and any positive side length, and the results update instantly.
How it works
The three ratios: SOH (sin = opp/hyp), CAH (cos = adj/hyp), TOA (tan = opp/adj). From angle and hypotenuse: opp = hyp × sin, adj = hyp × cos. From angle and opposite: hyp = opp / sin, adj = opp / tan. From angle and adjacent: hyp = adj / cos, opp = adj × tan. The other acute angle is always 90 degrees minus the given angle.
Worked example
With angle = 30 degrees and hypotenuse = 10: opposite = 10 × sin(30) = 10 × 0.5 = 5. Adjacent = 10 × cos(30) = 10 × 0.866 = 8.66. Hypotenuse = 10. Other angle = 90 minus 30 = 60 degrees. These match the pre-filled defaults above.
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