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41
In a right angled triangle ΔDEF, if the length of the hypotenuse EF is 12 cm, then the length of the median DX is:
Discuss
Answer & Solution
Answer: Option C
Solution:
Median of right angle
$$\eqalign{ & = \frac{{EF}}{2} \cr & = \frac{{12}}{2} \cr & = 6\,{\text{cm}} \cr} $$
42
In an equilateral triangle ABC, G is the centroid. Each side of the triangle is 6 cm. The length of AG is:
Discuss
Answer & Solution
Answer: Option C
Solution:
Triangles mcq solution image
In Equilateral triangle
$$\eqalign{ & AG:GD = 2:1 \cr & AD = \frac{{\sqrt 3 }}{2}a \cr & AD = \frac{{\sqrt 3 }}{2} \times 6 \cr & AD = 3\sqrt 3 \cr & 3 \to 3\sqrt 3 \cr & 1 \to \sqrt 3 \cr & AG = 2\,{\text{unit}} = 2\sqrt 3 \,{\text{cm}} \cr} $$
43
In case of an acute angled triangle, its orthocenter lies:
Discuss
Answer & Solution
Answer: Option A
Solution:
In acute angled triangle orthocenter is always inside the triangle
44
If the measure of the angles of a triangle are in the ratio 1 : 2 : 3 and if the length of the smallest side of the triangle is 10 cm, then the length of the longest side is:
Discuss
Answer & Solution
Answer: Option A
Solution:
Let angle = x, 2x, 3x
x + 2x + 3x = 180
(∵ Sum of internal angle of a Δ)
6x = 180°
x = 30°
So, angle = 30, 60, 90
Smallest side of Δ
= 1 unit
= 10 cm
Largest side of Δ
= 2 units
= 20 cm
45
In a triangle ABC, ∠A = 70°, ∠B = 80° and D is the incenter of ΔABC, ∠ACB = 2x° and ∠BDC = y°. The values of x and y, respectively are:
Discuss
Answer & Solution
Answer: Option B
Solution:
Triangles mcq solution image
∠C = 180 - (∠A + ∠B)
∠C = 180 - 150
2x = 30
x = 15°
Triangles mcq solution image
∠BDC = 90° + $$\frac{1}{2}$$ ∠A
∠BDC = 90° + $$\frac{1}{2}$$ × 70°
∠BDC = 90° + 35°
∠BDC = 125°
So value of x and y are = 15°, 125°
46
In ΔABC, AC = BC and ∠ABC = 50°, the side BC is produced to D so that BC = CD then the value of ∠BAD is:
Discuss
Answer & Solution
Answer: Option C
Solution:
Triangles mcq solution image
In ΔABC
∠B = ∠A = 50°
∠ACD = 50° + 50°
∠ACD = 100°
∠ACD is the external angle or ΔABC
∠ACD + ∠CAD + ∠ADC = 180°
∠CAD = ∠ADC
∵ AC = CD
2∠CAD = 180 - 100
∠CAD = 40°
∠BAD = 50° + 40°
∠BAD = 90°
47
An equilateral triangle of side 6 cm is inscribed in a circle. Then radius of the circle is:
Discuss
Answer & Solution
Answer: Option A
Solution:
$$\eqalign{ & R = \frac{a}{{\sqrt 3 }} \cr & R = \frac{6}{{\sqrt 3 }} \cr & R = 2\sqrt 3 \,{\text{cm}} \cr} $$
48
If ΔPQR and ΔLMN are similar and 3PQ = LM and MN = 9 cm, then QR is equal to:
Discuss
Answer & Solution
Answer: Option D
Solution:
Triangles mcq solution image
$$\eqalign{ & \frac{{PQ}}{{LM}} = \frac{{QR}}{{MN}} = \frac{{PR}}{{LN}} \cr & \left( {\vartriangle PQR\,{\text{and}}\,\vartriangle LMN\,{\text{are}}\,{\text{similar}}} \right) \cr & \frac{{PQ}}{{LM}} = \frac{{QR}}{{MN}} \cr & \frac{1}{3} = \frac{{QR}}{9} \cr & QR = 3\,{\text{cm}} \cr} $$
49
In a ΔABC, ∠A + ∠B = 75° and ∠B + ∠C = 140°, then ∠B is:
Discuss
Answer & Solution
Answer: Option B
Solution:
∠A + ∠B = 75° . . . . . . (i)
∠B + ∠C = 140° . . . . . (ii)
(we know)
∠A + ∠B + ∠C = 180° . . . . . . (iii)
from equation (i) & (iii)
∠C = 105° . . . . . . . . . . . . . . . (iv)
from equation (ii) & (iv)
∠B = 35°
50
ABC is an isosceles triangle where AB = AC which is circumscribed about a circle. If P is the point where the circle touches the side BC, then which of the following is true?
Discuss
Answer & Solution
Answer: Option A
Solution:
Triangles mcq solution image
here given that = AB = AC
AQ + BQ = AR + RC
we know that
BQ = PB & PC = RC
AQ + PB = AR + PC
also AQ = AR
AR + PB = AR + PC
PB = PC