This document provides information about calculating the surface area of different shapes, specifically trapezoids and farms. It includes the formulas for calculating surface area of a trapezoid and wetted canal cross-section. Examples are provided to demonstrate how to use the formulas. The importance of calculating surface area of farms is discussed in relation to determining irrigation needs. Learning objectives focus on identifying formulas, computing surface areas, and appreciating the significance of basic calculations.

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Learning Competency: Perform Estimation and
Basic Calculation
Learning Outcomes 4: Perform Estimation and
Basic Calculation
1.1 Wetted Cross Canal Section
1.2. Dimension of Cross-Section
1.3. Determination of the surface area of a farm
Code: TLE_AFHC7/8ID-0g-7

3. Learning Objectives:
At the end of the lesson, the students are
expected to:
1. determine the surface area of a farm.
2. follow the formula in calculating the
surface area and dimensions of a wetted
cross-section of a canal; and
3. appreciate the importance of calculating
the surface area of a farm.

4. Learning Objectives:
At the end of the lesson, the students
should be able to:
1. Identify the formula in getting the
surface area of a trapezium
2. Compute for the surface area of a
trapezium
3. Value the significance of knowing basic
calculation in computing the surface area
of a trapezium

5. REVIEW
FILL ME!
Directions: Fill in the blanks with the
correct word/s to complete the sentence.

6. 1. The height (h) of a triangle, a rhombus, a
parallelogram or a trapezium, is the distance from a
_Top corner to the opposite side called base.
2. The height is always perpendicular to the base; in
other words, the height makes a “ Right angle” with the
base.
3. In the case of a square or a rectangle, the expression
Length is commonly used instead of base and width
instead of height.
4. In the case of a circle, the expression . Diameter is
used.
5. The surface area of a triangle is calculated by _0.5 x
base x height

7. DIRECTIONS: Read each statement carefully. Write
T if the statement is correct and F if not. Write your
answer on your answer sheet.
1. A hectare is equal to 100, 000 square meters.
2. Wetted cross-section canal looks like a cross
shape.
3. The height or depth of the water in the canal
means from the bottom of the canal to the water
level.

8. 4. There are field that has an irregular in
shape. In this case, the field should be
divided in several regular areas.
5. It is necessary to determine the surface
area of a farmers field when calculating how
much irrigation water should be given to a
certain field.

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Trapezium
CROSS-SECTION
OF A CANAL
Week 9 3rd quarter
Janneth R. Centeno
Teacher 1

10. The most common shape of a canal cross-section
is a trapezium or, more truly, an "up-side down"
trapezium. It may be necessary to determine the
surface area of a farmer's field. For example, when
calculating how much irrigation water should be
given to a certain field, the size of the field must be
known. The shape field maybe regular o irregular
shape. If the shape field is irregular the field should
be divided in several regular areas such as square,
rectangle, triangle, etc.

13. SURFACE AREA OF THE WETTED CANAL
CROSS-SECTION = 0.5 (base + top line) x
water depth = 0.5 (b + a1)
Where: base (b) = bottom width of the canal
top line
(a1) = top width of the water level water depth
(h1) = the height or depth of the water in the
canal

15. Find the area of the following trapezium

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Assessment
Directions. Calculate the surface area of the wetted
cross-section. Write your answer on your answer sheet.
1. Canal wetted cross-section: base (b) = 1.75 m top
line (a1) = 3.75 m water depth (h1) =1.00 m
2. Canal wetted cross-section: base (b) = 1.5 m top line
(a1) = 3.5 m water depth (h1) =1.00 m

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Activity
 Directions: Measure your backyard
garden canal and compute the
surface area of it.Write your answer
on your notebook.10pts

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Assignment:
1.How to determine the surface
area of a farm?
2.What is the formula to compute
the surface area in hectare?

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DAY 2

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REVIEW

22. DIRECTIONS: Read and analyze each
statement carefully. Write the letter of the
correct answer.

23. 1.Which of the following statement is
TRUE about trapezium?
A. In a trapezium top and height run
parallel.
B. In a trapezium base, top and height
run parallel.
C. In a trapezium only the height and
base are parallel.
D. In a trapezium only the base and the
top run parallel.

24. 2. Which of the following is the formula in
getting the surface area of a trapezium?
A. 0.5 (base + top) x height
B. 0.5 (base x top) – height
C. 0.5 (base + top) - height
D. 0.5 (base - top) x height

25. 3. If a trapezium has 4 cm for base, top is 3
cm and height is 2 cm. What will be its
surface area?
A. 5 cm² B. 6 cm² C. 7 cm² D. 8 cm²

26. 4. The area of trapezium whose parallel sides
are 5 and 4 cm and the distance between
them is 6 cm. What will be its surface area?
A. 22 cm2 C.26 cm2
B.24 cm2 D. 27 cm2

27. 5. A trapezium lot has 40 and 50 cm
parallel sides and the distance between
them is 40cm. What will be its surface
area?
A. 1,500 cm2 C. 1,700 cm2
B.1,600 cm2 D.1,800 cm2

28. 1. D
2. A
3. C
4. D
5. D

29. DETERMINATION OF THE SURFACE AREA OF A
FARM
It may be necessary to determine the surface area
of a farmer's field. For example, when calculating
how much irrigation water should be given to a
certain field, the size of the field must be known.
When the shape of the field is regular and has a
rectangular shape, it should not be too difficult to
calculate the surface area once the length of the
field and the width of the field have been measured

35. WHAT’S MORE
Knowledge Power!
DIRECTIONS: Compute the surface area of
the following trapeziums. Write your solution
on a separate sheet of paper. Don’t forget to
write the unit of measurement.

36. 1. 6cm2
2. 6cm2
3. 2cm2

37. WHAT I HAVE LEARNED
Directions: Complete the statements below.
I have learned that (1pt.)
_________________________________________
I have realized that (2pts.)
________________________________________
I will apply (2 pts.)
_________________________________________

38. WHAT I CAN DO
Directions: Find the area of a table if its
parallel sides are 1m and 1.2m having a
perpendicular distance of 0.8m. Write your
solution on a separate sheet of paper. (5
points)

39. 0.88m2

40. Directions: Read and analyze the problem and
solve for what is needed. Write your solution and
your answer on your answer sheet.
1. During ECQ, Mr. Tumbaga and his son planted
vegetables on their vacant lot. Find the surface
area of the lot to be planted with vegetables, if
the size of the vacant lot is 45 meters long and
25 meters wide?
2. Find the surface area of a wetted cross-section
canal, if its base and top line are 1.25 meters and
3.25 meters respectively and has a depth of 1
meter?

41. ASSESSMENT
Directions: Compute for the surface area of the
following trapeziums. Write your solution on a
separate sheet of paper. Don’t forget to write
the unit of measurement.

42. Assessment
1. 32cm2
2. 35cm2
3. 99cm2
4. 38.5cm2
5. 34cm2

43. ADDITIONAL ACTIVITIES
Directions: Read and analyze the given
problem then answer what is being asked
for each number. Write your solution on a
separate sheet of paper. Don’t forget to
write the unit of measurement. (5points
each)

44. 1. The height of a trapezium is 18 m and the
top and base are 8 and 9m respectively.
Find the surface area.
2. Precious has a garden that is shaped like
a trapezium. Its height is 3.5 m and the top
and base are 5.5m and 6.6m. How many
square meter will be available to plant?

45. 3. Warren is building an orchard; which shape
is like a trapezium. The top and base are 4.4
m and 4.8m respectively and its height is 3m.
How many square meter is the orchard?
4. Find the area of a trapezium whose parallel
sides are 24 cm and 20 cm and the distance
between them is 15 cm.

46. Directions: Read each statement carefully. Write
your answer on your answer sheet.
1. A hectare is equal to _____ square meters.
2. It is from the bottom of the canal to the water
level.
3. The most common shape of wetted cross-
section canal
4. If the field has an irregular shape, what should
you do in several regular areas?
5. This is necessary to determine how much
irrigation water should be given to a certain field.