•Topic: Trig Propertes

Aim: how can we identify the reference angle given an angle terminating in other than quadrant I on the unit circle?

•Do Now: in a 45-45-90 right traingle, if the hypoutenuse is 1, what is the length of the the two legs?

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•Do Now Solution

•Using a 45-45-90 right triangle, if the hypotenuse is equal to 1, what is the length of the other two legs?

•Both legs are equal (45-45-90)

•Leg = 1/√2 = √2/2

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•Example 2

•Find the cos of 300°

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•Draw a unit circle and label the radius (=1)

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•Find the reference angle and refer to CHART

•ALL Students take Chemistry!

•Exact value chart – save to notes

•Example 1: Finding the reference angle

•Find the exact value of sin 120°

•Step 1: Which quadrant? (II)

So, only sin is + ; all others are –

•Step 2: Find reference angle: 180 – 120 = 60° - always makes angle with the x-axis!

• Step 3: identify sin 60° = √3/2 (see prev chart)

•Step 4: synthesize steps 1-3.

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•Therefore, the sin 120° = - √3/2

•Exit slip

Point            is  on  the unit circle

 whose center is the origin.  If Θ is an angle in standard position whose terminal ray passes through point A, what is the value of  sin Θ?