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The module contains only one lesson: Lesson 1: Solve problems involving parallelograms, trapezoids and kites. After going through this module you are expected ...
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Department of Education
Quarter 3 - Module 4:
Name of Learner: ___________________________
Grade & Section: ___________________________
Name of School: ___________________________
What I Need to Know
The module contains only one lesson: Lesson 1: Solve problems involving parallelograms, trapezoids and kites.
After going through this module you are expected to:
What I Know
Directions: Encircle the letter of the correct answer.
What is the measure of angle E?
A. 130^0 B. 110^0 C. 60^0 D. 50^0
What is the measure of the two sides? A. 1cm B. 3cm C. 5cm D. 7cm
What’s New
Activity 2: True or False! Directions : Write T if the statement is correct and if the statement is false write the correct word to make the statement correct. _________1. In a parallelogram, any two opposites sides are congruent (≅).
_________2. In a parallelogram, any two consecutive angles are congruent (≅). _________3. In a parallelogram, any two consecutive angles are complementary. _________4. A diagonal of a parallelogram from two congruent triangle. _________5. The median of a trapezoid is parallel (‖) to each base and its length is one third the sum of the lengths of the bases. _________6. The base angles of an isosceles trapezoid are congruent (≅). _________7. Opposite angles of an isosceles trapezoids are supplementary. _________8. The diagonals of an isosceles trapezoid are congruent (≅). _________9. The diagonals of a kite are perpendicular to each other. ________10. The area of a kite is half the product of the lengths of its diagonal.
What is it
The figure below shows the different kinds of quadrilateral. Each kind has its own properties.
QUADRILATERAL
Parallelogram Trapezoid
Rectangle Square Rhombus
Kite
Let us recall on the properties of a parallelogram Properties of a parallelogram.
These properties would help us solve problems involving parallelograms.
Let us try a look at this given example 1.
Given a parallelogram CAVE, CA=(x+6) cm and EV=(4x-15) cm CE=(2y+1) cm and AV= (y+3)cm.
Solution:
Since CA and EV, EC and AV are sides which are parallel and opposite to each other then
we can apply property number 1 which states that in a parallelogram opposite sides are congruent.
Given: CA=(x+6)cm EV=(4x-15)cm CA≅EV In a parallelogram , opposite sides are congruent. x + 6 = 4x – 15 By substitution x + 6 – 6 = 4x – 15 – 6 Addition Property of Equality x - 4x = 4x – 4x - 21 Addition Property of Equality -3x = - -3x = - -3 - x = 7 value of x
By substitution, solve for CA.
CA = (x+6)cm CA = (7 + 6)cm CA = 13cm Therefore, side CA is 13 cm
EV = (4x-15)cm Given EV = (4(7) – 15)cm Substitute the value of x=7 and simplify EV = (21-15) cm Subtract EV = 13cm Therefore, side CA and EV are congruent
CE=(2y+1)cm , AV= (y+3)cm. CE ≅ AV In a parallelogram, opposite sides are congruent. 2y+1 = y+3 By substitution 2y+1-1 = y+3-1 Addition Property of Equality 2y-y = y-y+2 Addition Property of Equality
x+
4 x- 15
Therefore, D and I are congruent.
Therefore the measure of K = 155^0.
Property number 4 says that the diagonal in a parallelogram bisect each other_._
Let us try a look at this given example 3. Given a parallelogram FACE , diagonal FC and AE intersect at M.
EM = (4x-2)cm and AM = (x+7)cm F A
To solve the problem used property number 4 which states that the diagonals of a
parallelogram bisect each other.
By substitution EM = (4x-2) cm EM = (4(3) – 2) cm EM = (12 – 2) cm EM = 10 cm
Therefore, EM is 10 cm long
Example 4. A rectangular lot has a width of (2b + 4) cm and (b + 7) cm and its length is (3a+ 5) cm and (2a + 16) cm. a. What is the width of the rectangular lot? b. What is the length of the rectangular lot? c. Find the perimeter of the lot.
Since a rectangle is a parallelogram then we can apply the property which states that in a parallelogram opposite sides are congruent.
Solution: a. What is the width of the rectangular lot? (2b + 4) cm = (b + 7) cm In a parallelogram, opposite side are congruent 2b + 4 = b+ 7 2b – b + 4 – 4 = b + 7 – 4 Addition Property of Equality b = 3 value of b By Substitution: (2b + 4) cm = (b + 7) cm (2(3) + 4) cm = (3 + 7) cm (6 + 4) cm = 10 cm 10 cm = 10 cm Therefore, the width of the rectangular lot is 10cm and its width are congruent.
Example 1. Quadrilateral HEAT is an isosceles trapezoid with HE ‖ TA. BD is its median. If HE=(x+10) cm , A = (3x – 2) cm and BD = 20 cm, find the length of the two bases.
Using property number 1 and 2:
The two bases of the isosceles trapezoid.
Solution:
E = (3x-17)^0 Given E= (3(30)-17)^0 Substitute the value of x=30 and simplify E = (90-17)^0 E = 73^0 The measure of angle E
b. Is the measure of E ≅ K? K = (2x + 13)^0. Given K = (2(30) + 13)^0 Substitute the value of x= K = (60 + 13)^0 K = 73^0 The measure of angle E The measure of E ≅ K c. What is the measure of L? L is opposite to K L + K = 180^0 Opposite angles in an isoscele trapezoid are supplementary L + 73^0 = 180^0 Substitute L + 73^0 -73^0 = 180^0 - 73^0 Addition Property of Equality L = 180^0 - 73^0 Addition Property of Equality L = 107^0 The measure of L
To find the length of LK To find the length of AE LK = (4x+3)cm AE=(2x + 5)cm LK = (4(1)+3)cm AE=(2(1) + 5)cm LK = (4+3)cm AE=(2 + 5)cm LK = 7cm the length of LK AE= 7cm the length of AE Therefore diagonal LK and AE in an isosceles trapezoid are congruent.
Example 2. The area of the kite is 90cm^2 and the length of the diagonal is 18cm.How long is the other diagonal? Solution: A = 1 (d 1 d 2 ) Area of the kite is ½ the product of the 2 length of its diagonal. 90cm^2 = 1 (18cm) (d 2 ) By substitution 2 90cm^2 = 18cm (d 2 ) Simplify 2 90cm^2 = 9cm (d 2 ) 90cm^2 = 9cm (d 2 ) 9cm 9cm 10cm = d 2 d 2 = 10cm the length of the other diagonal in a kite.
What’s More
Activity 3: Try Me! Directions: Solve the following problems involving parallelograms, trapezoid and kite. State the property used to solve the problems. Write your answer on the space provided and use extra sheets for your solution.
What I Have Learned Activity 4. Paired Me Up Directions: Choose your answer in the box. Write the correct answer on the space provided.
480 56cm 800 7cm 45cm
____1. The diagonals of a kite have lengths of 14cm and 8cm. Find the area of the kite. ____2. If the measure of one angle of an isosceles trapezoid is x^0 and the angle opposite it is (x+20)^0 , what is the measure of the smaller angle? ____3. Liza wishes to bake a rectangular cake with the parallel side measures (3x+4) cm and (2x + 5) cm, what is the length of the side?
____4. An isosceles trapezoid MILD where MI ‖ DL with AB as median. If MI=(2x+7) cm, LD=(x-3) cm and AB= 34 cm. How long is DL?
____5. ABCD is a kite. AB is adjacent to BC and diagonal AC and BD intersect at E. If BEA =(15x)^0 and BAE = 8x-6, find the m ABC.
What I Can Do
Activity 5: Feel Me! Direction: Illustrate the problem and solve. Write your answer on the space provided and use extra sheets for your solution.
Assessment
Multiple Choice Test: Encircle the letter of the correct answer.
What is the length of ET? A. 3cm B. 6cm C. 12cm D. 24cm
How long is RN? A. 5cm B. 8cm C. 10cm D. 18cm
Mathematics 9 3 RD^ QUARTER MODULE 4 Answer Key
What I know
What’s In Activity 1
What’s New Activity 2
What’s More Activity 3
What I have learned Activity 4
What I can do Activity 5
Assessment
References:
Bryant, Merden L., Leonides E. Bulalayao, Melvin M. Callanta, Jerry D. Cruz, et al. Mathematics Learner’s Material 9. Pasig City: Department of Education, 2014.
Bryant, Merden L., Leonides E. Bulalayao, Melvin M. Callanta, Jerry D. Cruz, et al.Mathematics Teachers Guide 9. Pasig City: Department of Education, 2014
Bernabe, Julieta G., Soledad Jose-Dilao and Fernando B Orines, Quadrilaterals Geometry, 1251 Gregorio Araneta Avenue, Quezon City: SD Publications Inc., 2009.
Development Team
Writer: ANALIZA S. LAPAD
Illustrator: Layout Artist: