ICSE Class X Math 2015 Solved Paper
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Question : 12
Total: 52
In the figure given below, O is the centre of the circle and S P is a tangent. If ∠ S R T = 65 ∘ , find the value of x , y and z .
Solution:
In △ OSP,∠ OSR = 90 ∘
[Radius is perpendicular to tangent]
In∆ TSR
x + 90 ∘ + 65 ∘ = 180 ∘
(Angle sum property of triangle)
∴ x = 25 ∘
∠ SOQ = 2 ∠ STR
[Angle at centre= 2 × Angle at circumference]
y = 2 × 25 = 50 ∘
In∆ OSP,
50 ∘ + 90 ∘ + z = 180 ∘
(Angle sum property of triangle)
∴ z = 40 ∘
[Radius is perpendicular to tangent]
In
(Angle sum property of triangle)
[Angle at centre
In
(Angle sum property of triangle)
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