If 7 tan θ = 3, then (7 sin θ + 5 cos θ) ⁄ (7 sin θ − 2 cos θ) is:

- (a)8
- (b)6
- (c)5
- (d)7
Answer
Why
Correct — A. The stem is an image: if 7 tan θ = 3, find (7 sin θ + 5 cos θ) ⁄ (7 sin θ − 2 cos θ). Divide every term, top and bottom, by cos θ.
(7 sin θ + 5 cos θ) ⁄ (7 sin θ − 2 cos θ)
= (7 tan θ + 5) ⁄ (7 tan θ − 2)
Substitute the group 7 tan θ = 3 as it stands
= (3 + 5) ⁄ (3 − 2) = 8 ⁄ 1 = 8 → option (a)
Why the others are wrong
- (b)6 — For the value to be 6, (7 tan θ + 5) ⁄ (7 tan θ − 2) = 6 solves to 7 tan θ = 17⁄5 = 3.4. The stem fixes it at 3, so the denominator is exactly 1 and the value is 8.
- (c)5 — This is the numerator with the 3 dropped. After the division by cos θ the numerator is 7 tan θ + 5 = 3 + 5 = 8, and it is the denominator, not the numerator, that collapses to 1.
- (d)7 — 7 is the coefficient the paper puts in front of both sine terms, and it cancels nothing on its own. Substituting sin θ = 3⁄√58 and cos θ = 7⁄√58 gives 56⁄√58 ÷ 7⁄√58 = 8.
Concept
A fraction whose numerator and denominator are both first degree in sin and cos is homogeneous: divide both lines by cos θ and every term becomes a tan θ term. The angle itself is never needed.
Here the stem gives 7 tan θ = 3 rather than tan θ = 3⁄7, and the fraction is built so that 7 tan θ appears intact in both lines. Substitute the group, not the isolated value, and the arithmetic is two subtractions long.
The denominator lands on exactly 1, which is why the answer is a clean integer rather than a surd.
If your working leaves a √58 that will not cancel, you substituted sin and cos separately — not wrong, just slower, and it reaches the same 8.
Key facts
- Dividing a homogeneous sin-cos ratio by cos θ turns every term into a tan θ term.
- With 7 tan θ = 3, the expression reduces to (3 + 5) ⁄ (3 − 2) = 8.
- tan θ = 3⁄7 corresponds to sin θ = 3⁄√58 and cos θ = 7⁄√58.
Study next
Common traps
- Reading 7 tan θ = 3 as tan θ = 3 and substituting 3 for the tangent.
- Dividing through by sin θ instead of cos θ, which leaves cot terms and more work.
- Cancelling the 7 sin θ that appears in both lines, which is not a common factor of either line.
The stem here is a single typeset line with no text at all, so reading it is part of the test.
Quant Q.8 of the 12 Sep 2024, 12:30 sitting is the same shape — an image expression whose keyed value is 2 cosec — so the reading skill and the identity work are tested together.
Related PYQs
No directly related past PYQ was found.