A right-triangle question asking for tangent is asking for a side-length ratio, not the angle itself. Start at the marked angle to identify the leg across from it and the leg touching it. Use opposite over adjacent. Reversing those legs flips the fraction; using the hypotenuse gives a different ratio.
Hints
- Hint 1
The hypotenuse is the side across from the right angle, even though it also touches the marked acute angle. Set it aside for tangent. Which two sides are left?
- Hint 2
Stand at to name the legs. The opposite leg is across from it, and the adjacent leg touches it. Tangent uses opposite over adjacent. Which labeled leg goes in each spot?
Step-by-step
Name the legs from the marked angle
Step 1Set aside the hypotenuse
No Desmos needed. The figure labels both legs, so you can read their ratio directly. The right angle is at , so , across from it, is the hypotenuse. Tangent doesn't use the hypotenuse.
- Step 2
Name the legs from
From at , is across the triangle, so it's the opposite leg. touches and isn't the hypotenuse, so it's the adjacent leg. Use , not , or you'll switch their roles.
- Step 3
Write the tangent ratio
The tangent ratio is opposite leg over adjacent leg, so use the two legs you named: . So equals . Choice A.