Find the exact value of: sin405.
reference angle=225
sin225= -.707106781
= -.71
No. That isn't right.
sin 405 = sin 45 = + 0.70711
The reference angle is 45 degrees (405 -360) and you are in the first quadrant.
To find the exact value of sin 405, we need to find the reference angle first.
To find the reference angle, we can subtract multiples of 360 from the given angle (405) until we get an angle between 0 and 360 degrees.
In this case, we can subtract 360 from 405 to get 45 degrees. So, the reference angle is 45 degrees.
Since the sine function is negative in the third and fourth quadrants (180-360 degrees), we can use the reference angle to find the sine value.
The sine of 45 degrees is equal to √2 / 2 by using special triangles or trigonometric identities.
Since the reference angle is in the third quadrant, the sine value will be negative.
So, sin 405 = - (√2 / 2) = -0.707106781 or approximately -0.71.