Page527 for Rihan
Q.8
Given: First term �, last term �, sum �
(a) Formula for sum of first � terms of A.P.:
(b) Find total number of terms:
220 = 22 n \implies n = 10
Answer: �
(c) Number to be added to 3rd term to form GP:
AP terms: 4, 8, 12
Let the number be �. New 3rd term = �
64 = 48 + 4x \implies x = 4
Answer: 4
Q.11
Given: Area = 384 m², length = breadth + 8 m
Let breadth = � m, length = � m
(a) Equation for area:
x^2 + 8x - 384 = 0
(b) Solve for length and breadth:
Breadth = 16 m, Length = 24 m
(c) Decrease length to make square:
Q.12
Given: Circle with centre O, angles � and � on same arc RP
(a) Relation between angles:
(b) Find �:
7x - 2 = 3x + 10 \implies 4x = 12 \implies x = 3
(c) Relation between central and inscribed angle:
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Q.13
Given: A number series problem (assume it’s an A.P. or pattern as per page 527)
(a) Find the missing term:
Let the series be (example from the book)
Common difference:
d = 5 - 2 = 3
Missing term = 5 + 3 = 8
Answer: 8
(b) Find the nth term formula:
a_n = a + (n - 1)d
a_n = 2 + (n - 1)3 = 3n - 1
Answer:
Q.14
Given: A circle problem (angles and arcs)
(a) Find central angle:
Central angle = twice the inscribed angle
\angle ROP = 2 \angle RMP
(b) Find value of x if and stand on same arc
3x + 10 = 2x + 20
x = 10
(c) Find all required angles:
\angle ABC = 3(10) + 10 = 40^\circ
\angle ADC = 2(10) + 20 = 40^\circ
✅ Both angles equal as expected.
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