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Grade 9 Mathematics Module: Law of Sines and Its Applications

This Self-Learning Module (SLM) is prepared so that you, our dear learners, can continue your studies and learn while at home. Activities, questions, directions, exercises, and discussions are carefully stated for you to understand each lesson.

Each SLM is composed of different parts. Each part shall guide you step-by-step as you discover and understand the lesson prepared for you.

Pre-tests are provided to measure your prior knowledge on lessons in each SLM. This will tell you if you need to proceed on completing this module or if you need to ask your facilitator or your teacher’s assistance for better understanding of the lesson. At the end of each module, you need to answer the post-test to self-check your learning. Answer keys are provided for each activity and test. We trust that you will be honest in using these.

Please use this module with care. Do not put unnecessary marks on any part of this SLM. Use a separate sheet of paper in answering the exercises and tests. And read the instructions carefully before performing each task.

In the previous modules, you have learned how to solve right triangle using trigonometric functions. Now you will learn to solve non-right triangles called oblique triangles. Any triangle, right or oblique, may be solved using the Law of Sines and the Law of Cosines. If any three of the six measures of a triangle are given, provided at least one measure is a side, then the other three measures can be found. An oblique triangle is a triangle that does not have a right angle. There are laws or formulas that describe the relationships between the angles and the sides of an oblique triangle. These are the Law of Sines and the Law of Cosines.

After going through with this module, you are expected to be able to illustrate law of sines.

Grade 9 Mathematics Quarter 4 Self-Learning Module: Law of Sines and Its Applications


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