238,401 views
24 votes
24 votes
If 0 < f ≤ 90 and cos(22f − 1) = sin(7f + 4), what is the value of f?

User Ergo
by
3.2k points

2 Answers

14 votes
14 votes

Answer:

The answer is "3."

Explanation:

Just submitted the test and got the answer correct!

User Dimuthu
by
2.7k points
18 votes
18 votes

Answer:

3

Explanation:

We are going to be using cofunction identity cos(90-x)=sin(x).

Apply to either side but not both.

cos(22f − 1) = sin(7f + 4)

sin(90-[22f-1])=sin(7f+4)

90-[22f-1]=7f+4

Distribute

90-22f+1=7f+4

Combine like terms

91-22f=7f+4

Add 22f on both sides

91=29f+4

Subtract 4 on both sides

87=29f

Divide 29 on both sides

3=f

f=3 is between 0 and 90

User Criz
by
3.2k points
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