
Introduction to Trig Ratios
Presentation
•
Mathematics
•
9th - 12th Grade
•
Medium
Standards-aligned
Pam Darden
Used 223+ times
FREE Resource
10 Slides • 8 Questions
1
Introduction to Trig Ratios
What To Do When the Pythagorean Theorem Just Won't Cut It!
2
Why Do We Need Trigonometry?
Sometimes, we aren't given enough information to use the Pythagorean Theorem.
Sometimes, we need to find angle measures with only the right angle given!
3
Where is trigonometry used in the real world?
* Video Game Design
* Speaker Placement in Concert Venues
* Architecture/Construction
* Criminology
* Military
4
The Basics
* Trigonometry only works with RIGHT triangles in Geometry.
* Given a specific angle (reference angle), you need to label the sides of the triangle as being opposite of, adjacent to (which means next to), or the hypotenuse, which is ALWAYS across from the right angle!
5
Notice This!
* The hypotenuse will ALWAYS be labelled as the hypotenuse-no matter where it is in relation to the reference angle.
* Which sides are opposite and adjacent depends on which angle is the reference angle.
*HELPFUL HINT! If you highlight the entire reference angle, those sides will ALWAYS be the hypotenuse and the adjacent sides!
6
Multiple Choice
What is the side ADJACENT to the reference angle?
RT
TK
RK
7
Multiple Choice
Which is the side OPPOSITE of the reference angle?
GN
GW
WN
8
Multiple Choice
Which side is the HYPOTENUSE of the triangle?
KT
KR
TR
9
Trigonometric Ratios
The ratios formed by the side lengths of a right triangle.
*We use these to solve for missing sides and/or missing angles of right triangles.
10
sine (sin)
hypotenuseopposite
The sin function is the ratio of the
length of the side opposite the reference angle over the length of the hypotenuse.
11
cosine (cos)
The cosine of an angle is the ratio of the length of the side ADJACENT to the reference angle to the length of the HYPOTENUSE.
12
tangent (tan)
The tangent is the ratio of the side OPPOSITE the reference angle over the length of the side ADJACENT to the reference angle.
13
How Will I Remember All of Those Ratios?????
Here's How!
14
Multiple Choice
Which ratio represents
cos(∠W) ?
158
1715
178
15
Multiple Choice
Which ratio represents
tan(∠W) ?
178
1715
158
16
Multiple Choice
Which ratio represents
sin(∠S) ?
2920
2021
2921
17
Multiple Choice
Which ratio represents
cos(∠S) ?
2021
2921
2920
18
Multiple Choice
Which ratio represents
tan(∠S) ?
2120
2921
2021
Introduction to Trig Ratios
What To Do When the Pythagorean Theorem Just Won't Cut It!
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