ACT · Trigonometry · Graphs of sine and cosine
Question act-q-00553
Easy Multiple choice No calculator
The question
What is the value of sin(30°)?
- ½
- √3/2
- 0
- 1
Show answer & worked solution
Answer: ½
Worked solution. Recall the unit circle: sin(30°) = ½.
Why each wrong choice is wrong. The classic distractor swaps sine and cosine values for the same angle. Drilling the unit circle eliminates this entirely.
Test-day tactic. Memorize sine and cosine at 0°, 30°, 45°, 60°, and 90°. The values are short and they appear constantly.
About this question type
Items test the basic shape of sine and cosine graphs and the effect of changing amplitude, period, and phase shift.
You will see a question shaped like this one on roughly every other official ACT form, typically at an early position in the section, where missing them carries an outsize penalty because the curve assumes everyone in your band gets them right. Treat any miss in this subtopic as a signal to drill the subtopic page before you do another full practice test.