Question

solve 5sin^2+3cos^2=4​

Answer 1

5sin²@+3cos²@=4

2sin²@+3sin²@+3cos²@=4

2sin²@+3(sin²@+cos²@)=4

2sin²@+3=4

2sin²@=1

sin²@=1/2

sin@=1/√2

but, sin45=1/√2

therefore,

@=45°

hope it helps