Question

Find the value of y. Round your answer to the nearest tenth.

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Answer 1

Usually in geometry to find the required value you can apply one of the following or their combination:

• Pythagorean theorem
• Sine law
• Cosine law
• Projections using one of the trigonometrical functions
• Different formulas, properties, axioms and theorems.

For instance, consider the following problem: find the value of y - length of an arc:

Calculate the projection of the 'diagonal':

$$d=30\text{sin}30^\circ=15,$$

calculate the length of an arc:

$$y=2\pi d/4=\pi d/2=7.5\pi.$$