Question

plz with full steps​

Answer 1

Answer:

4/5

Step-by-step explanation:

angle d+phi+theta =180

(sum of angles of a triangle)

thus,

angle d=90-phi

similarly,

angle a=90-theta

theta + phi + 90=180

(total angle of a straight line is 180)

theta + phi=90

theta = 90- phi

substituting in angle a

angle a = 90- 90+phi

therefore,

angle a= phi

thus,

cos phi= adjacent/hypotenuse

=4/5

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