Radians and Angles Welcome to Trigonometry!! Starring The Coterminal Angles Supp & Comp Angles The Converter And introducing… Angles Rad Radian Degree
THE UNIT CIRCLE You & I are gonna be great friends!
Angle- formed by rotating a ray about its endpoint (vertex) Initial Side Starting position Terminal SideEnding position Standard Position Initial side on positive x-axis and the vertex is on the origin
Angle describes the amount and direction of rotation 120°–210° Positive Angle- rotates counter-clockwise (CCW) Negative Angle- rotates clockwise (CW)
1 Radian = measure of central angle, , that intercepts the arc that has the same length as the radius of the circle Arc length “s” = radius when = 1 radian
Calculate the number of radians in one full circle: C = 0 , 2 0, 6.28 Therefore, we can say that 1 full revolution = 2 radians.
Coterminal Angles:Two angles with the same initial and terminal sides Find a positive coterminal angle to 20º Find 2 coterminal angles to Find a negative coterminal angle to 20º
Now, you try… Find two coterminal angles (+ & -) to What did you find? These are just two possible answers. Remember…there are more!
Complementary Angles: Two angles whose sum is 90 Supplementary Angles: Two angles whose sum is 180
To convert from degrees radians, multiply by To convert from radians degrees, multiply by Convert to radians:
To convert from degrees radians, multiply by To convert from radians degrees, multiply by Convert to degrees: So, you think you got it now?
1 degree = 60 minutes 1° = 60 1 minute = 60 seconds 1 = 60 So … 1 degree = _________seconds 3600 Express 36 5010 as decimal degrees
OR Use your calculator!! Express 36 5010 as decimal degrees Enter 36 Press this button ’ ’’ Press enter Enter 50 Press this button ’ ’’ Go over to the ’ symbol -- enter Enter 10 Press this button ’ ’’ Go over to the ’’ symbol -- enter Press enter
Convert 50 47’ 50’’ to decimal degree Convert 125 27’ 6’’ to decimal degree Can you go backwards and convert the decimal degree to degrees minutes seconds? Enter Go to DMS hit enter.
Express in degrees, minutes, seconds 50º +.525(60) 50º º (60) 50 degrees, 36 minutes, 30 seconds