Sin -270 different from sin - 90 exact and aprox values?

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In summary, to find the exact value of sin(-270), we can use the reference angle of +90 degrees to determine that sin(90 deg.) = 1, which is the exact value. This is different from the approximate value of 1 obtained by plugging it into a calculator.
  • #1
Senjai
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Homework Statement



Homework related question:Write the exact value of sin(-270)

The Attempt at a Solution



I had this same question before but to write it in approximate value. for an aprox value i simply just plug it into my calculator and get: 1. Pretty exact for an approximate value. When i solve it the exact way. (No calculator) i determine that the Reference angle for -270 degrees is -90 degrees. then i sin -90 degrees and get -1. The answer is 1. I don't understand.
 
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  • #2
Senjai said:

Homework Statement



Homework related question:Write the exact value of sin(-270)

The Attempt at a Solution



I had this same question before but to write it in approximate value. for an aprox value i simply just plug it into my calculator and get: 1. Pretty exact for an approximate value. When i solve it the exact way. (No calculator) i determine that the Reference angle for -270 degrees is -90 degrees. then i sin -90 degrees and get -1. The answer is 1. I don't understand.
The reference angle for -270 degrees is +90 degrees. sin(90 deg.) = 1, exactly.
 
  • #3
Oh! Ref angles are always positive.. sorry.. Thanks for your time!
 

Related to Sin -270 different from sin - 90 exact and aprox values?

1. What is the difference between sin -270 and sin -90?

Sin -270 and sin -90 are both trigonometric functions that deal with angles. The main difference between the two is the direction in which the angle is measured. Sin -270 is measured clockwise from the positive x-axis, while sin -90 is measured counterclockwise from the positive x-axis.

2. Are the exact values of sin -270 and sin -90 different?

Yes, the exact values of sin -270 and sin -90 are different. Sin -270 has an exact value of -1, while sin -90 has an exact value of -1/√2.

3. What are the approximate values of sin -270 and sin -90?

The approximate values of sin -270 and sin -90 can be found using a calculator or a trigonometric table. Sin -270 has an approximate value of -0.9998, while sin -90 has an approximate value of -0.7071.

4. Why do sin -270 and sin -90 have different values?

Sin -270 and sin -90 have different values because they represent different angles. The angle -270 degrees is equivalent to 3 revolutions in a counterclockwise direction, while the angle -90 degrees is equivalent to 1/2 revolution in a counterclockwise direction. Therefore, they have different positions and different values.

5. How can I use the values of sin -270 and sin -90 in trigonometric equations?

The values of sin -270 and sin -90 can be used in trigonometric equations to solve for unknown angles or sides of a triangle. They can also be used to find the sine of other angles by using the trigonometric identities and properties.

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