Valmiki Ramayana Sundara Kanda Sarga 37 Shloka 33
Original Shlokaइति सञ्चिन्त्य हनुमांस्तदा प्लवगसत्तमः। दर्शयामास वैदेह्यास्स्वरूपमरिमर्दनः।।5.37.33।।
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प्लवगसत्तमः the noble monkey, अरिमर्दनः crusher of enemies,हनुमान् Hanuman, इति in that way, सञ्चिन्त्य thinking that way, तदा then, स्वरूपम् his real form, वैदेह्याः to Vaidehi, दर्शयामास he revealed.
Thinking thus, Hanuman, the noble monkey, crusher of enemies, started revealing his real form to Vaidehi.