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Lesson Example Discussion Quiz: Class Homework

Step-3

Title: Area of Triangle(Based on Angles)

Grade: 4-a Lesson: S2-L6

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Step	Type	Explanation	Answer
1	Problem	Calculate the area of an obtuse-angled triangle with side lengths of 8 units, 10units, and an included angle of 120 degrees.
2	Step	Given that the sides of a triangle are 8 units and 10 units.
3	Step	Given angle is 120°
4	Formula	The area of an obtuse-angled triangle, you can use the formula:	\$1/2 \times "a" \times "b" \times sin(C)\$
5	Step	Now plug the values into the formula	A = \$1/2 \times 8 \times 10 \times sin(120°)\$
6	Step	After simplification the value we get	A = \$1/2 \times 80 \times sin(120°)\$
7	Clue	sin 120° = \$\sqrt(3)/2\$
8	Step	Now place the sin120° value.	A = \$1/2 \times 80 \times \sqrt(3)/2\$
9	Step	After simplification the value we get	A = \$20 \sqrt(3)\$
10	Step	So, the area of the obtuse-angled triangle is \$ 20 \sqrt 3\$ square units.
11	SumUp	Can you summarize what you’ve understood in the above steps?
12	Choice.A	The received answer for this problem doesn’t align with option 22\$\sqrt 3\$ sq. units, making it incorrect	22\$\sqrt 3\$ sq.units
13	Choice.B	The answer for this problem is equivalent to the one provided in option 20\$\sqrt 3\$ sq.units, making it the correct choice	20\$\sqrt 3\$ sq.units
14	Choice.C	The received answer for this problem doesn’t align with option 10\$\sqrt 3\$ sq. units, making it incorrect	10\$\sqrt 3\$ sq.units
15	Choice.D	The received answer for this problem doesn’t align with option 20\$\sqrt 2\$ sq. units, making it incorrect	20\$\sqrt 2\$ sq.units
16	Answer	Option	B
17	SumUp	Can you summarize what you’ve understood in the above steps?

Step

Type

Explanation

Answer

Problem

Calculate the area of an obtuse-angled triangle with side lengths of 8 units, 10units, and an included angle of 120 degrees.

Step

Given that the sides of a triangle are 8 units and 10 units.

Step

Given angle is 120°

Formula

The area of an obtuse-angled triangle, you can use the formula:

\$1/2 \times "a" \times "b" \times sin(C)\$

Step

Now plug the values into the formula

A = \$1/2 \times 8 \times 10 \times sin(120°)\$

Step

After simplification the value we get

A = \$1/2 \times 80 \times sin(120°)\$

Clue

sin 120° = \$\sqrt(3)/2\$

Step

Now place the sin120° value.

A = \$1/2 \times 80 \times \sqrt(3)/2\$

Step

After simplification the value we get

A = \$20 \sqrt(3)\$

Step

So, the area of the obtuse-angled triangle is \$ 20 \sqrt 3\$ square units.

SumUp

Can you summarize what you’ve understood in the above steps?

Choice.A

The received answer for this problem doesn’t align with option 22\$\sqrt 3\$ sq. units, making it incorrect

22\$\sqrt 3\$ sq.units

Choice.B

The answer for this problem is equivalent to the one provided in option 20\$\sqrt 3\$ sq.units, making it the correct choice

20\$\sqrt 3\$ sq.units

Choice.C

The received answer for this problem doesn’t align with option 10\$\sqrt 3\$ sq. units, making it incorrect

10\$\sqrt 3\$ sq.units

Choice.D

The received answer for this problem doesn’t align with option 20\$\sqrt 2\$ sq. units, making it incorrect

20\$\sqrt 2\$ sq.units

Answer

Option

SumUp

Can you summarize what you’ve understood in the above steps?