y=2x-24° — (1)
x+y=180° (Sum of adjacent angles of a parallelogram)
3x-24°=180°
3x=180°+24°
3x=204°
x=204°/3
x=68°
Substituting in equation (1)
y=136°-24
y=112°
Hence, (c) 112°, would be the correct option.
Doubt Questions of CBSE Class 9th Students
Question : The value of (√32 + √48) / (√8 + √12) is equal to
(a) √2
(b) 2
(c) 4
(d) 8
Doubt by Suraj
Solution :
(√32 + √48) / (√8 + √12)
=(√48 + √32) / (√12 + √8)
=(4√3 + 4√2) / (2√3 + 2√2)
Rationalising the denominator
=(4√3 + 4√2) × (2√3 - 2√2) / (2√3 + 2√2)×(2√3 - 2√2)
=[4√3(2√3 - 2√2) + 4√2(2√3 - 2√2)] / [(2√3)² - (2√2)²]
[∵(a+b)(a-b)=(a²-b²)]
=[8×3-8√6+8√6-8×2] / [12-8]
=[24-0-16] / 4
=[8]/4
=2
Hence, (b) 2, would be the correct option.
Question : If 52x-1-25x-1=2500, find the value of x.
Doubt by Bhumika
Solution :
52x-1-25x-1=2500
52x-1-(52)x-1=2500
52x-1-52x-2=2500
52x-1-52x-1-1=2500
52x-1-52x-1÷51=2500
52x-1(1-1/5)=2500
52x-1(4/5)=2500
52x-1=[2500×5]/4
52x-1=3125
52x-1=55
Comparing the exponents both sides
2x-1=5
2x=5+1
2x=6
x=6/2
x=3
Question : Given below is a circle with O. Find the value of ∠BCD in terms of a and b.
(a) 180°+(a-b/2)
(b) 180°-(a+b/2)
(c) 180°-(a-b/2)
(d) None of these.
Doubt by Vikrant
Solution :