Math Problem Statement
Draw a right-angled triangle containing an angle of 45°. If one of the shorter sides has length one, write down the lengths of the other sides without using trigonometry. Hence find the exact values of sin 45°, cos 45° and tan 45°.
Solution
To solve this problem, we start by drawing a right-angled triangle with one angle of 45°. In a right-angled triangle, the two non-right angles must sum to 90°. Therefore, if one of these angles is 45°, the other must also be 45°. This makes the triangle an isosceles right-angled triangle, where the two legs are of equal length.
Given that one of the shorter sides (one leg of the triangle) has a length of 1, we can determine the lengths of the other sides as follows:
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Both legs are equal in length: Since the triangle is isosceles and one leg is 1, the other leg is also 1.
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Hypotenuse calculation: The length of the hypotenuse (let's denote it as ) can be found using the Pythagorean theorem, which states:
Substituting the known lengths:
Thus, .
Now, we can find the exact values of the trigonometric functions for the 45° angle:
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:
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:
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:
For exact values, we often rationalize the denominators:
Thus, the exact values are:
Would you like any further explanation or have any questions about these results?
Here are 5 questions you might consider asking next:
- How can we use trigonometry to find the area of the triangle?
- What are the properties of isosceles right-angled triangles?
- Can you explain why the sine and cosine of 45° are equal?
- How do you rationalize a fraction with a square root in the denominator?
- What are some real-life applications of right-angled triangles?
Tip: In trigonometry, rationalizing denominators is often done to simplify expressions, making them easier to work with or recognize.
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Math Problem Analysis
Mathematical Concepts
Trigonometry
Right-angled triangles
Isosceles triangles
Formulas
Pythagorean theorem
Theorems
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Suitable Grade Level
Grades 9-12
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