I do acknowledge those references, sites, and pictures that I use to have this ppt.

1. A Very Bless
Day to
Everyone!

2. Let’s Play Trigo

3. 𝜃

4. Oblique
Triangles

5. a. Illustrate the laws of sine and
cosine
b. Solve problems involving
oblique triangles
c. Show mastery in applying the
laws of sine and cosine in solving
problems oblique triangles

6. Law of sine states that a side
divided by the sine of the angle
opposite it is equal to any other
side divided by the sine of the
opposite angle
𝑠𝑖𝑛𝐴
𝑎
=
𝑠𝑖𝑛𝐵
𝑏
=
𝑠𝑖𝑛𝐶
𝑐

7. When to use Law of Sine
It can only be used if:
Two angles and a side are
known; or
Two sides and an angle opposite
one of them are known

8. When to use Law of Cosine
It can only be used if:
the three sides are known; and
the two sides and its included
angle are known
𝑐2
= 𝑎2
+ 𝑏2
− 2𝑎𝑏 cos 𝐶

9. Problem 1:
In G-9 Cattleya there was a
presentation in Mathematics, one of
the group present their work as the
teacher estimated, she ask the
students to find how far is the
presenter from the TV, given the
illustration on the next slide.

10. ?
What Law to be applied?
Law of sine

13. Problem #2:
Given three sides find ∠𝐴, ∠𝐵 𝑎𝑛𝑑 ∠𝐶 :
𝑎 = 10; 𝑏 = 15, 𝑐 = 20
What Law to be applied?
Law of Cosine

17. a. What do you
mean by oblique
triangle?

18. b. What are your
thoughts about the
applications of laws
of sines and cosines?

19. b. What are your
thoughts about the
applications of laws
of sines and cosines?

21. Groupings
3 mins. preparation and 2 mins
presentation

22. Ram and Mar went to Balete coast to fly a kite.
Ram’s kite has1750ft. of string at an angle of 75°.
Mar notes that the angle formed by the kite and
the flier is 102°. How far is Mar from the kite? Mar
from Ram?

25. G3. 𝑥 = 120°
G4. 𝑥 = 11.24°
G5. 𝑥 = 65°

26. “Beat Us if You
Can”

27. • When you raise your answer that
is final.
• First to raise, power to eliminate
other group
• Being eliminated means not
included in game
• 3 seconds to decide which group
to be eliminated

28. Given the
illustration,
what law to
be applied?Law of
sine

29. This means that there is
no right angle in the
triangle.
Oblique triangle

30. Given the illustration, what law
to be applied?
Law of Cosine

31. Law to be used when
three sides are known
Law of Cosine

32. What law apply in this
formula
𝑐2
= 𝑎2
+ 𝑏2
− 2𝑎𝑏 cos 𝐶
Law of Cosine

33. What is the formula for
Law of Sine?
𝒔𝒊𝒏𝑨
𝒂
=
𝒔𝒊𝒏𝑩
𝒃
=
𝒔𝒊𝒏𝑪
𝒄

35. Exercise# 4.__Answer the following questions
using the figure.
1. How far is the Ranger’s Tower from the fire?
2. How far is the Ranger’s Tower from the Water
Tower?

36. 1. 𝑥 = 202.4771 𝑜𝑟
202.48𝑓𝑡.
2. 𝑥 = 266.2761 𝑜𝑟
266.28𝑓𝑡.

37. ASSIGNMENT #4.___
Create and illustrate a
situation that shows the
application of law of sine and
cosine in short-bond paper.