Latest posts by QuizTablet (see all)

## If sine x equals cosine x, what is x in radian?

**A.** π/4

**B.** π/2

** C.** π/3

**D.** π/12

**QUICK ANSWER…**

**A**

**DETAILS…**

**Here, we are required to find the value of x so that sin x is the same as cos x.**

**Now we know that sin 45 is the same thing as cos 45 = 1/√2**

**Also, we know that π = 180****°, therefore, 45° = 180/4 = π/4**

**This is the quickest solution, however, there's a longer solution:**

**sin x = cos x**

**sin²x = cos²x**

**but recall that cos²x + sin²x = 1**

**substituting cos²x for sin²x, we have:**

**sin²x + sin²x = 1**

**2sin²x = 1**

**sin²x = ½**

**sin x = √½ = 1/√2**

**x = sin¯¹ 1/√2 = 45°** = **π/4**

**Now for the right answer to the above question:**

**Option A is correct.****Option B is incorrect.****C is incorrect.****D is not the correct answer.**

**KEY-POINTS…**

**You may please note these/this:**

**Cos 45° = sin 45°****180° = π****45° = π/4****If you love our answers, you can login to comment and say hi to us at the comment section…**

**To raise new related question****s, c****lick the ASK A QUESTION BOTTON down this page…**

**/ culled from 2020 JAMB-UTME mathematics past question 10 /**