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91
ABCD is a square and ΔMAB is an equilateral triangle. MC and MD are joined. What is the degree measure of ∠MDC?
Geometry mcq question image
Discuss
Answer & Solution
Answer: Option D
Solution:
Geometry mcq question image
∠A = ∠B = ∠D = ∠C = 90°
ΔAMB is equilateral
Hence ∠A = 60°
∠DAM = 90° + 60° = 150°
∠ADM $$ = \frac{{{{180}^ \circ } - {{150}^ \circ }}}{2} = \frac{{{{30}^ \circ }}}{2} = {15^ \circ }$$
∠MDC = 90° - 15° = 75°
92
Two chords of length $$a$$ unit and $$b$$ unit of a circle make angles 60° and 90° at the centre of a circle respectively, then the correct relation is:
Discuss
Answer & Solution
Answer: Option A
Solution:
Geometry mcq question image
∠AOB = 60°
∠COD = 90°
⇒ length of chord AB = a
⇒ length of chord CD = b
⇒ AO = OB = AB = OD = OC = a
⇒ In ΔODC
⇒ OD2 + OC2 = CD2
⇒ a2 + a2 = b2
⇒ b = $$\sqrt 2 $$ a
93
In a triangle ABC, P and Q are point on AB and AC, respectively, such that AP = 1 cm, PB = 3 cm, AQ = 1.5 cm and CQ = 4.5 cm. If the area off ΔAPQ is 12 cm2, then find the area of BPQC.
Geometry mcq question image
Discuss
Answer & Solution
Answer: Option A
No explanation is given for this question. Let's Discuss on Board
94
If in the given figure, ∠ACB + ∠BAC = 80°, ∠BDE = 35°, ∠BCE = 45°, then the marked angle ∠CED is:
Geometry mcq question image
Discuss
Answer & Solution
Answer: Option C
Solution:
Geometry mcq question image
∠BAC + ∠ACB = ∠CBD
80° = ∠CBD
∠CBD = 80°
Let, GH || BD
∠DEH = 35°
∠CGE = 80°
∠CGE + ∠GCE = ∠CEH
80° + 45° = ∠CEH
∠CEH = 125°
∠DEH + ∠CEH = ∠CED
125° + 35° = ∠CED
∠CED = 160°
95
ABC is a cyclic triangle and the bisectors of ∠BAC, ∠ABC and ∠BCA meet the circle at P, Q and R respectively. Then the angle ∠RQP is:
Discuss
Answer & Solution
Answer: Option A
Solution:
Geometry mcq question image
From chord BP
∠BAP = ∠BQP = z
(Angle subtended by same chord on circumference)
Similarly from chord RB
∠RCB = ∠RQB = y
In ΔABC
2x + 2y + 2z = 180°
x + y + z = 90°
y + z = 90° - x
∠RQP = 90° - x
∠RQP = $${90^ \circ } - \frac{{\angle {\text{B}}}}{2}$$
96
In the given figure, AB, AC and EF are tangents to a circle. If AC = 15 and DE = 3 cm. Then the length of AE is:
Geometry mcq question image
Discuss
Answer & Solution
Answer: Option D
Solution:
DE = EB = 3 cm (tangent at same point)
AE + EB = AB = AC (tangent at same point)
AE + 3 = 15
AE = 12 cm
97
In a ΔABC, ∠BAC = 90° and AD is perpendicular to BC where D is a point on BC. If BD = 4 cm and CD = 5 cm, then the length of AD is equal to:
Discuss
Answer & Solution
Answer: Option C
Solution:
Geometry mcq question image
AD2 = BD × CD
AD2 = 4 × 5
AD = 2√5
98
Length of the sides of a triangle are a, b and c respectively. If a2 + b2 + c2 = ab + bc + ca then the triangle is
Discuss
Answer & Solution
Answer: Option B
Solution:
a2 + b2 + c2 = ab + bc + ca
This is true only when a = b = c
So, triangle will be equilateral.
99
In a trapezium ABCD, DC || AB, AB = 12 cm and DC = 7.2 cm. What is the length of the line segment joining the midpoints of its diagonals?
Discuss
Answer & Solution
Answer: Option D
Solution:
Geometry mcq question image
$${\text{MN}} = \frac{{12 - 7.5}}{2} = \frac{{4.8}}{2} = 2.4$$
100
A triangle with the lengths of its sides proportional to the numbers 7, 24 and 30 is:
Discuss
Answer & Solution
Answer: Option B
Solution:
Geometry mcq question image
Let, Perpendicular = 7 cm
Base = 24 cm
Hypotenuse = 30 cm
Here, P2 + B2 < C2
(7)2 + (24)2 < (30)2
49 + 576 < 900
625 < 900
Therefore triangle is obtuse angled triangle.