ACT Math : How to find positive sine

研究概念, example questions & explanations for ACT Math

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Example Questions

Example Question #1 :How To Find Positive Sine

If, what is? Round to the nearest hundredth.

Possible Answers:

Correct answer:

Explanation:

回想一下,正弦波symmetrical with respect to the origin. Therefore, for any value, the value foris. Therefore, ifis, then for, it will be.

Example Question #71 :Trigonometry

In a right triangle, cos(A) =. What is sin(A)?

Possible Answers:

Correct answer:

Explanation:

In a right triangle, for sides a and b, with c being the hypotenuse,. Thus if cos(A) is, then c = 14, and the side adjacent to A is 11. Therefore, the side opposite of angle A is the square root of, which isSince sin is, sin(A) is.

Example Question #72 :Trigonometry

51213

What is the value of?

Possible Answers:

Correct answer:

Explanation:

As with all trigonometry problems, begin by considering how you could rearrange the question. They often have hidden easy ways out. So begin by noticing:

Now, you can treatlike it is any standard denominator. Therefore:

Combine your fractions and get:

Now, from our trig identities, we know that, so we can say:

Now, for our triangle, theis. Therefore,

Example Question #21 :Sine

Solve for:

if

Possible Answers:

Correct answer:

Explanation:

Recall that the standardtriangle, in radians, looks like:

Rt1

Since, you can tell that.

Therefore, you can say thatmust equal:

Solving for, you get:

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