Question

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感謝你 200分。
緊急. 數學

Answer 1

QUESTION :

1. secA.sin(36+A)=1

2. sin5A = cos4A

TO FIND :

A =?

SOLUTION :

1. secA.sin(36+A)=1

so sin(36+A)=1/secA

sin(36+A)=cosA...........((1/secA)=cosA)

so sin(36+A)=sin(90-A).........sinA=cos(90-A)

now by cancelling sin on both the sides

36 +A=90-A

2A=90-36

A=54/2

A=27°

2. sin5A = cos4A

so sin5A=sin(90-4A).........sin(90-A)=cosA

so by cancelling sin in both sides

5A=90-4A

9A=90

A=10°

hence the value of A in

1. is 27°

2. is 10°

NOTE :

here A is equal to theta