
In the given right-angled triangle, where the lengths of the sides given are in cm, find the value of cos α + cot α
- AOption (a)
- BOption (b)
- COption (c)
- DOption (d)
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Correct answer
Why this answer is correct
Shortcut Trick
Identify sides relative to angle α: Opposite = 8 cm, Hypotenuse = 17 cm.
Apply Pythagorean triplet (8, 15, 17) → Adjacent = 15 cm.
cos α = Adjacent/Hypotenuse = 15/17 and cot α = Adjacent/Opposite = 15/8.
Sum = 15/17 + 15/8 = (120 + 255) / 136 = 375/136.
∴ The correct answer is 375/136.
Alternate Method
Given: Perpendicular (p) = 8 cm, Hypotenuse (h) = 17 cm.
Formula Used: b2 = h2 − p2; cos α = b/h; cot α = b/p
⇒ Base (b) = √(172 − 82)
⇒ b = √(289 − 64) = √225 = 15 cm
⇒ cos α = 15/17
⇒ cot α = 15/8
⇒ cos α + cot α = (15/17) + (15/8)
⇒ LCM of 17 and 8 = 136
⇒ (15 × 8 + 15 × 17) / 136 = (120 + 255) / 136 = 375/136
∴ The correct answer is 375/136.
Additional Information
Pythagorean Triplets
Sets of three integers (a, b, c) that satisfy a2 + b2 = c2, such as (3, 4, 5), (5, 12, 13), and (8, 15, 17).
Trigonometric Ratios
For a right triangle: sin = p/h, cos = b/h, tan = p/b, cosec = h/p, sec = h/b, and cot = b/p.
Relationship between Tan and Cot
cot α = 1 / tan α = cos α / sin α.




