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Question:

State whether the following are true or false. Justify your answer. (i) The value of tanA is always less than 1. (ii) secA = 12/5 for some value of angle A. (iii) cosA is the abbreviation used for the cosecant of angle A. (iv) cotA is the product of cot and A. (v) sinθ = 4/3 for some angle θ.

Solution:

(i) False. If B = 90°, AB = 3, BC = 4, AC = 5, tanA = 4/3 > 1. (AC² = AB² + BC²) (ii) True. AC² = AB² + BC² (12x)² = (5x)² + BC², BC = √119x (it is possible). Pythagoras theorem (iii) False. cosA is cosine A, cscA is cosecant. (iv) False. cotA = cotangent of ∠A, not product of cot and A. (v) False. sinθ = perpendicular/hypotenuse. sinθ > 1; 4/3 > 1 is not possible. [hypotenuse > base > perpendicular] sinθ will always be less than 1.