NIMCET 2014 — Mathematics PYQ
NIMCET | Mathematics | 2014In △ABC, if a=2, b=4 and ∠C=60∘, then A and B are respectively equal to:
Choose the correct answer:
- A.
90∘,30∘
- B.
45∘,75∘
- C.
60∘,60∘
30∘,90∘
Explanation
Concept
For a triangle:
-
Cosine rule: cosC=2aba2+b2−c2
-
Sine rule: sinAa=sinBb=sinCc
Where A, B and C are the angles of the triangle and a, b and c are sides opposite to angle A, B and C respectively.
Calculation
Given a=2, b=4 and ∠C=60∘.
1. Find side c using the Cosine rule:
2. Find angle A using the Sine rule:
3. Find angle B using the Angle Sum Property:
Correct Option: 4
Explanation
Concept
For a triangle:
-
Cosine rule: cosC=2aba2+b2−c2
-
Sine rule: sinAa=sinBb=sinCc
Where A, B and C are the angles of the triangle and a, b and c are sides opposite to angle A, B and C respectively.
Calculation
Given a=2, b=4 and ∠C=60∘.
1. Find side c using the Cosine rule:
2. Find angle A using the Sine rule:
3. Find angle B using the Angle Sum Property:
Correct Option: 4
