Trig Equations and CAST Diagram

Which quadrant stands for 180-a ?

• C

• A

• S

• T

Which quadrant stands for 360-a ?

• C

• A

• S

• T

Which quadrant stands for 180+a ?

• C

• A

• S

• T

Select all the quadrants where sinx is positive

• C

• A

• S

• T

Select all the quadrants where cosx is positive

• C

• A

• S

• T

Select all the quadrants where tanx is positive

• C

• A

• S

• T

How do you solve

tanx = 2

• divide by tan

• subtract tan

• find tan^-1(2)

• can't solve it as 2 > 1

Solve

sinx = 1

for x between 0 and 360 degrees

• x = 90

• x = 1

• x = 90 and 180

• x = 0 and 90

Solve

sinx + 1 = 1.5

for x between 0 and 360 degrees

• x = 30

• x = 30 and 150

• x = 30 and 330

• x = 30 and 150 and 330

Solve

cosx - 1 = -0.5

for x between 0 and 360 degrees

• x = 60

• x = 30 and 60

• x = 60 and 300

• x = 30 and 60 and 300