NIMCET 2010 — Mathematics PYQ
NIMCET | Mathematics | 2010In a triangle ABC, where A=(−4,2), B=(2,1) and C=(−4,−5), find ∠ACB.
Choose the correct answer:
- A.
30∘
- B.
45∘
(Correct Answer) - C.
25∘
- D.
60∘
45∘
Explanation
1. Slope of line CA (m1):
Points: C(−4,−5) and A(−4,2)
Since the slope is undefined, line CA is a vertical line (parallel to the y-axis).
2. Slope of line CB (m2):
Points: C(−4,−5) and B(2,1)
3. Angle Calculation:
The angle θ between a vertical line and a line with slope m is given by:
Since CA is vertical (x=−4) and the slope of CB is 1:
The angle that CB makes with the positive x-axis is 45∘ (because tan45∘=1).
A vertical line makes an angle of 90∘ with the x-axis.
Correct Option:
(b) 45°
Explanation
1. Slope of line CA (m1):
Points: C(−4,−5) and A(−4,2)
Since the slope is undefined, line CA is a vertical line (parallel to the y-axis).
2. Slope of line CB (m2):
Points: C(−4,−5) and B(2,1)
3. Angle Calculation:
The angle θ between a vertical line and a line with slope m is given by:
Since CA is vertical (x=−4) and the slope of CB is 1:
The angle that CB makes with the positive x-axis is 45∘ (because tan45∘=1).
A vertical line makes an angle of 90∘ with the x-axis.
Correct Option:
(b) 45°
