□ABCD is cyclic. If ∠A =(7y - 21) ° and ∠C = (4y+3)° . Find measure of ∠A.
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Given:
∠A =(7y - 21)°
∠C = (4y+3)°
To find:
The measure of angle A
Solution:
The measure of angle A is 105°.
We can find the angle by following the given steps-
We know that ABCD is cyclic.
So, the angles at opposite ends will be supplementary.
Here angle A and angle C are opposite to each other.
The sum of angle A and angle C is equal to 180°.
Angle A+Angle C=180°
Angle A=(7y-21)° and Angle C=(4y+3)°.
Substituting the values of angle A and C, we get
(7y-21)+(4y+3)=180°
7y-21+4y+3=180
11y-18=180
11y=180+18
11y=198
y=198/11
y=18°
Now, to find the measure of angle A, we can put the value of y.
Angle A=7y-21
On putting y=18°, we get
Angle A=7×18-21
=126-21
Angle A=105°
Therefore, the measure of angle A is 105°.
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