Detailed lesson plan in mathematics

1. I. Objectives:Atthe endof the lesson75% of the studentwill be able to:
Illustrate andsolve atriangle giventhe measureof the twoparts
II. SubjectMatter:Triangle Trigonometry
References:MathematicslearnersModule grade 9page 437
Materials:ManilaPaper,marker, Chalk,Bondpaper,Projector.
Strategy:Interactive Instruction
ValuesInfusion:Cooperativeness
III. Procedures
Teachers Activity Student Activity
A. Preliminaries
Good AfternoonClass
Kindlysitdown.
A.1 Checkingof attendance
Say presentif yourname iscalled.
B. Review:
Last meetingourtopicwas,
How to use calculatorinfinding
the Degree,minutes,seconds.
C. Motivation:
Since our topicwasthe use of calculatorlast meeting
So letstryif understandhoware the functionsof your
calculatorwill enough.
Try solvingthis:
1. Cos 0 = 0.739
2. Cos 58
0= 42.340 sir.
= 0.5299
D. Classinsolvinga triangle meansthatwe have tofindits
missingmeasurementsof itspartsand since we are
givenlengthof the hypotenuse andthe lengthof one
legwhatare we goingto use to find it.
Example 1.
Triangle BCA isright –angledat C.If c=23 andb =17 ,
find Angle A,Angle B,anda . Expressyouranswersup
to twodecimal places.
Solution:Sketchafigure:

2. a. Side bis the adjacentside of Angle A ; c is the
hypotenuse of the righttriangle BCA .Use CAH, That is
Cos A =
𝑏
𝑐
Cos A =
17
23
Cos A =
We can use our scientificcalculatortofind an angle
whose cosine value is0.7391.
Usinga scientificcalculatorA = 42.340 degrees
b. Since inpart a it was alreadyfoundthatangle A = 42.34
degrees,thenAngleB= 90 – 42.34
Angle B= 47.66
c. Usingthe Pythagoreantheorem:
𝑎2 + 𝑏2 = 𝑐2
Substitute the valesof the measurementof the sidesthatis
𝑎2 + (17)2 = (23)2
Since that isthe valuesletstrysolvingit.
𝑎2 + 289 = 528
𝑎2 = 240
𝑎 = √240
What isthe value of oura class
E. Activity1.
Group yourselvesin9 ina certaingroup.
Try answeringthe followingin yourgroup.
I will give youabondpaper where youcanwrite your
solutions.
Sketcha figure andsolve eachrighttriangle ABCwith
rightangle at C, giventhatfindthe missing
measurements.
. a = 15.8, b = 21
Cos 𝜃 =
𝐴𝑑𝑑𝑗𝑎𝑐𝑒𝑛𝑡
𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒
0.7391 sir.
42.340 degreessir.
𝑎2 + (17)2 = (23)2
a = 15.49.
F. Generalization:
What isthe formulasyouhave use tosolve the missing
measurementsof the triangleclass.
IV. Evaluation:
Sketcha figure andsolve eachrighttriangle ABCwithrightangle at C, andthe missing
measurementsof the triangle giventhat:
1. a = 250, b = 250
V. Assignments
Readpart B inpage 437 inyour Mathematicsbook.