$( A) \ 55^{o}$

$( B) \ 70^{o}$
$( C) \ 45^{o}$
$( D) \ 35^{o}$"
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In fig. 1, O is the centre of a circle, PQ is a chord and PT is the tangent on P. if $\angle POQ=70^{o}$, then $\angle TPQ$ is equal to:


$( A) \ 55^{o}$

$( B) \ 70^{o}$
$( C) \ 45^{o}$
$( D) \ 35^{o}$"


Given: fig.1 a circle with centre O, a chord PQ, a tangent PT on P and ∠POQ=70°

To do: To find out $\angle TPQ=?$ 

Solution: 
here in the given figure 

O is the centre of the circle 

OP is the radius of the circle and also OQ is the radius of the circle. 

$\therefore \ OP=OQ$

In $\vartriangle OPQ$, OP and OQ are equal.

$\therefore \ \angle OPQ=\angle OQP$

$\Rightarrow \angle POQ+\angle OPQ+\angle OQP=180^{o}$ 

$\Rightarrow 70^{o} +\angle OPQ+\angle OQP=180^{o}$                                $( \because \angle POQ=70^{o}\ as\ given\ in\ the\ question)$

$\Rightarrow 2\angle OPQ=180^{o} -70^{o} =110$                                          $( \because \angle OPQ=\angle OQP)$

$\Rightarrow \angle OPQ=\frac{110^{o} }{2} =55^{o}$

It is also given the question that TP is a tangent on P.

$\therefore\ \angle OPT=90^{o}$

And $\angle OPQ+\angle TPQ=\angle OPT=90^{o}$ 

$\Rightarrow 55^{o} +\angle TPQ=90^{o}$

$\Rightarrow \angle TPQ=90^{o} -55^{o} =35^{o}$

$\therefore$ Option $( D)$ is correct.

Updated on: 10-Oct-2022

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