Sine Cosine Relationship in Right Triangles

Sine Cosine Relationship in Right Triangles

Complementary Angles

• The two(2) acute angles in a right triangle are complementary

• If one angle is  $\theta$  , then the second is  $90-\theta$  

• Sin A = a/c and Cos B = a/c because they look at same sides.  The opposite side from A is a and the adjacent side from B is a.

•  $Sin\left(\theta\right)=Cos\left(90-\theta\right)\ and\ Cos\left(\theta\right)=Sin\left(90-\theta\right)$  

Multiple Choice

Which two(2) functions are equal to 8/17?

• Sin A and Sin B

• Cos A and Cos B

• Sin A and Cos B

• Sin B and Cos A

Multiple Choice

If cos B = 3/5, which one of the following is also equal to 3/5?

• Cos A

• Sin A

• Sin B`

• Tan A

Multiple Choice

Cos(42^o)=0.743 approximately. Which of the following must also equal 0.743(approx.)?

• Sin(42^o)

• Cos(48^o)

• Sin(48^o)

• Sin(21^o)

Multiple Choice

 $\angle A\ and\ \angle B$  are the acute angles in a right triangle. $Cos\ A=\frac{3}{5},\ Sin\ A=\frac{4}{5},\ and\ Tan\ A=\frac{4}{3}$ .  Which is the value of 

Cos B? 

• 3/4

• 4/3

• 3/5

• 4/5

Multiple Choice

 $\angle E\ and\ \angle F$  are the two(2) acute angles in a right triangle.  If Tan E = 1, which of the following is NOT true?

• Sin E = Cos F

• Sin F = Cos E

• Sin E = Sin F

• Tan E = Tan F

• There are no options that are not true.  They're all true.