Plane Geometry
- In an equilateral Δ ABC, if AD ⊥ BC, then which option is true?
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Lat AB = BC = AC = a
AB2 = AD2 + BD2 (Pythagoras Theorem)
Correct Option: C
Lat AB = BC = AC = a
AB2 = AD2 + BD2 (Pythagoras Theorem)a2 = AD2 + a2 4 3a2 = AD2 4
- In the given figure, AB || DC, find the value of x.
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As we know the diagonals of a trapezium divide each other proportionally
∴ AO = BO OC OD
Correct Option: C
As we know the diagonals of a trapezium divide each other proportionally
∴ AO = BO OC OD 3x - 19 = x - 3 x - 5 3
⇒ 3(3x - 19) = ( x - 3 ) ( x - 5 )
⇒ 9x - 57 = x2 - 8x +15
⇒ x2 - 17x + 72 = 0
⇒ x = 8 or x = 9
- In the adjoining figure ∠A + ∠B + ∠C + ∠D + ∠E + ∠F = ?
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In ΔACE
∠A + ∠C + ∠E = 180°
Similarly in ΔDFB
∠D + ∠F + ∠B = 180°Correct Option: C
In ΔACE
∠A + ∠C + ∠E = 180°
Similarly in ΔDFB
∠D + ∠F + ∠B = 180°
∴ (∠A + ∠C + ∠E) + (∠D + ∠F + ∠B) = 360°
∠A + ∠B + ∠C + ∠D + ∠E + ∠F = 360°
- In ΔABC, the angle bisectors of ∠B and ∠C meet at O. If ∠A = 70°, then ∠BOC is equal to:
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As we know the formula,
∠BOC = 90° + 1 ∠A 2
Correct Option: B
As we know the formula,
∠BOC = 90° + 1 ∠A 2 ∴∠BOC = 90° + 1 (70°) = 90° + 35° 2
∠BOC = 125°
- The complement of an angle exceeds the angle by 60°. Then the angle is equal to:
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Let, the angle be A
⇒ Its complement angle = 90° – A
According to the question
(90 – A) = A + 60°Correct Option: C
Let, the angle be A
⇒ Its complement angle = 90° – A
According to the question
(90 – A) = A + 60°
⇒ 90 - 60 = A + A
⇒ 2A = 30°
⇒ A = 15°