Question

97th one . Plz answer fast.

Answer 1

Answer:

Step-by-step explanation:gahwhehebbjsjsgenxjejdbbd

Answer 2

Answer:

Proved that ∠A + ∠B = 90°

Step-by-step explanation:

Given: that A and B are acute angles of triangle ABC.

And  $sinA = CosB$

To prove: ∠A + ∠B = 90°

Prove:

 Given that

       $sinA = CosB$...............(1)

As given that A and B are acute angles of triangle ABC.

( Acute angle is an angle smaller than a right angle. The range of an acute angle is between 0 and 90 degrees.)

Therefore, $cosB$ can be written as $sin(90-B)$

Because   $sin(90-B)$ is in 1st quadrant and in 1st quadrant sin  change to cosecant .

So $cosB$  can be written as $sin(90-B)$ .

Therefore, equation (1) can be written as

   $sinA = sin(90-B)$  

        $A = 90-B\\A+B=90$  

Hence proved.