Painless Trigonometry


Sine of A

Given      cosA=\displaystyle\frac{2}{5}.    What is sin2A if A is on the 4th quadrant?


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Correct answer were submitted by:

1. Nivlem Alas-as. MSEUF Lucena City. 4th Year High School

2. Arsh Singh. India

3. Kenny Wong, Jurong Junior College, Singapore

4.  Jerome Bechayda. Laguna State Polytechnic University,San Pablo City Campus

5. John Rey Jimenez. Negros Occidental High School.

6. Jomari Tan. DLSU

7.Sebastian Pineda Berrio. Colombia

8. Hrushikesh Bhope. St Xavier’s High School. India

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3 Responses

  1. kryptonj123 says:

    Please review your solution

  2. kryptonj123 says:

    The correct answer for this problem is $latex \frac{-4\sqrt21}{25}$

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