Question

In any quadrilateral ABCD, prove that (i) sin(A + B) + sin(C + D) = 0, (ii) cos(A + B) = cos(C + D).​

Answer 1

Answer:

$\sqrt[ \sqrt[ \sqrt{ \sqrt{ \sqrt{ \sqrt{ \sqrt{ \sqrt{ \sqrt{ \sqrt[555 {?}^{?} \times \frac{?}{?} ]{?} } } } } } } } ]{?} ]{?}$

Step-by-step explanation:

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$11 \sqrt[ \sqrt[?]{?} ]{?}$

Answer 2

Answer

In a quadrilateral ABCD, ∠A+∠B+∠C+∠D=360

(i) sin(A+B)+sin(C+D)=2sin(

2

A+B+C+D

).cos(

2

A+B−C−D

)

=2sin(180).cos(

2

A+B−C−D

)

=0

(ii) cos(A+B)−cos(C+D)=−2sin(

2

A+B+C+D

).sin(

2

A+B−C−D