Choosing the Ratio
Part of the Right-Triangle Trigonometry section of Coddy's Trigonometry journey. Lesson 6 of 46.
Many wrong answers come from choosing the ratio before naming the sides. Name the sides first.
A 9 m ladder leans at 40° to the ground. Look from the 40° angle. The distance from the foot to the wall touches the angle, so it is adjacent. The ladder is the hypotenuse. Adjacent and hypotenuse means cosine.
- SOH: sine is opposite over hypotenuse.
- CAH: cosine is adjacent over hypotenuse.
- TOA: tangent is opposite over adjacent.
Challenge
A 7 m ladder leans on a wall. At the top, it makes 25° with the wall. How far is its foot from the wall? Find x to 2 decimal places.
Then press Check.
Try it yourself
Use the figure to find x