7.2 Finding a Missing Side of a Triangle using Trigonometry

STEP 1: Which angle is given?Angle B = 48º

STEP 2: Which two sides are given?Adjacent and Hypotenuse

STEP 3: Which Trig Ratio should you use?Cosine

€

cos48 =

€

22

x

STEP 1: Which angle is given?Angle B = 48º

STEP 2: Which two sides are given?Adjacent and Hypotenuse

STEP 3: Which Trig Ratio should you use?Cosine

€

x(cos48) =22

x

⎛

⎝ ⎜

⎞

⎠ ⎟x

STEP 1: Which angle is given?Angle B = 48º

STEP 2: Which two sides are given?Adjacent and Hypotenuse

STEP 3: Which Trig Ratio should you use?Cosine

€

x(cos48) =22

x

⎛

⎝ ⎜

⎞

⎠ ⎟x

€

x(cos48) = 22

STEP 1: Which angle is given?Angle B = 48º

STEP 2: Which two sides are given?Adjacent and Hypotenuse

STEP 3: Which Trig Ratio should you use?Cosine

€

x(cos48) =22

x

⎛

⎝ ⎜

⎞

⎠ ⎟x

€

x(cos48)

(cos48)=

22

(cos48)

€

x =22

(cos48)=

€

32.8785

STEP 1: Which angle is given?Angle B = 55º

STEP 2: Which two sides are given?Adjacent and Opposite

STEP 3: Which Trig Ratio should you use?€

tan55 =

€

x

10

Tangent

STEP 1: Which angle is given?Angle B = 55º

STEP 2: Which two sides are given?Adjacent and Opposite

STEP 3: Which Trig Ratio should you use?

€

10(tan55) =x

10

⎛

⎝ ⎜

⎞

⎠ ⎟10

€

10(tan55) = x

Tangent

STEP 1: Which angle is given?Angle B = 55º

STEP 2: Which two sides are given?Adjacent and Opposite

STEP 3: Which Trig Ratio should you use?

€

10(tan55) =x

10

⎛

⎝ ⎜

⎞

⎠ ⎟10

€

10(tan55) = x

€

x =10(tan55) =

€

14.2815Tangent