- A
- B
- C
- D
Step-by-Step Solution
si45° = , co30° = , ta45° = 1. So the value is . The answer is negative because the last term is the largest.
Answer: D)
Evaluate: 2 si45° + 3 co30° − 4 ta45°.
Class 10Introduction to TrigonometryTrigonometry
Key idea: Why ratios — and not lengths
Two right triangles with the same acute angle θ are SIMILAR (Class 10 ch. 6 — AA criterion: both have a right angle and the angle θ).
Similar triangles → corresponding sides in fixed ratio.
So the ratio (opposite / hypotenuse) takes the SAME value in any right triangle with angle θ — regardless of how big the triangle is.
That's why sin θ, cos θ, tan θ are FUNCTIONS of the angle alone — they're well-defined.
This is the fundamental reason trigonometry works as a clean theory.
Similar triangles → corresponding sides in fixed ratio.
So the ratio (opposite / hypotenuse) takes the SAME value in any right triangle with angle θ — regardless of how big the triangle is.
That's why sin θ, cos θ, tan θ are FUNCTIONS of the angle alone — they're well-defined.
This is the fundamental reason trigonometry works as a clean theory.
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More Class 10 Introduction to Trigonometry practice
Arrange sin 30°, cos 45° and tan 30° in increasing order of value.If sin 3A = cos(A − 26°), where 3A is an acute angle, find A.If tan 2A = cot(A − 18°), where 2A is an acute angle, find A.Find the value of tan 5° · tan 25° · tan 45° · tan 65° · tan 85°.For an acute angle θ, simplify √1 - ^2 θ/ ^2 θ.